Dacoity
Dada
Daguerreotype
Dahabiyeh
Dak
Dakin's Solution
Dalmatic
Dam
Damask
Damaskeening
Dammar Gum
Dance
Danegeld
Dark Ages
Dark Room
Darlington Pair
Data
Daturine
Davis cup
Day
Daylight Saving Time
dBM
Ddt
De Haeretico Comburendo
Decahydro-naphthalene
Decalin
Decathlon
Deceleration
Decibel
Declaration of Independence
Declaration of Indulgence
Declaration of Paris
Decoy
Defamation
Defence of the Realm Acts
Deimos
Dekatron
Deliquescence
Deliquescent
Delta
Delta Metal
Delta Rays
Denaturant
Density
Dentil
Dentistry
Denudation
Deodand
Depilatory
Deposition
Derating
Dermatitis
Desiccator
Desk
Devonian
Dew
Dextrin
Dialect
Diallyl barbituric acid
Dialogue
Diastase
Diathermy
Diazo Compounds
Dichroic Mirror
Didjeridu
Die-casting
Dielectric
Dietetics
Diethyl-barbituric acid
Diffusionism
Diflunisal
Digamma
Digested
Digestion
Digitalis
Dihydroxysuccinic acid
Dilatometer
Dimethyl-xanthine
Dimethylmethane diethylsulphone
Dimity
Dimorphism
Dinghy
Diode
Diphenyl
Diphtheria
Dipole aerial
Dipsomania
Dipyridamole
Disinfectant
Disopyramide
Disorderly House
Displacement
Dissection
Distributor
Diuretic
Dixie
Doctor Wind
Dog Days
Domesday Book
Dominoes
Doomsday book
Doppler effect
DORA
Down's syndrome
Dragon's Blood
Dram
Drams
Draughts
Dredger
Drill
Dropsy
Dry Ice
Dry Joint
Dry Rot
Dry-dock
Dulcimer
Duma
Dungeon
Duralumin
Duress
Dutch East India Company
Dutch West India Company
DWIM
Dye
Dyke
In the Penal Code, dacoity is defined as organised banditry by 5 or more persons. The word derives from the Hindustani word for a robber, dakait.
The dada is an artistic and literary movement founded in 1915 in Zurich.
Daguerreotype was the earliest process of photographic reproduction, and was so called after its inventor Louis Daguerre. A copper plate, polished and silvered, was sensitised by exposure to iodine vapour, and so coated with a fine layer of silver iodide. It was then exposed in a camera, like modern photographic film, but with a longer exposure time. It was afterwards removed and treated with mercury vapour, the mercury attaching itself to those areas which had been most exposed to light and settling there in a density proportionate to the strength of the light.
A dahabiyeh is a broad, shallow-draught vessel with a sharp prow and sails used for conveying passengers on the Nile.
Dak was the east Indian postal service. Properly a dak was a relay of men carrying letters, despatches and the like.
Dakin's Solution is a disinfectant solution containing sodium hydrochlorite, rendered neutral by the addition of boric acid as a buffer. The disinfectant action of the solution is very rapid, but it has the disadvantage of being unstable and does not keep for more than about a week.
A dalmatic is a sleeveless embroidered vestment worn by deacons in the Roman Church and the High Church section of the Anglican Church during the celebration of High Mass and at processions.
A dam is a structure constructed to hold back water and provide controlled flow for irrigation, storage and generation of electricity.
Damask is a material of silk, linen, etc., with a raised of flat pattern woven into it, and shading alternately light and dark, according to the angle of view. The name derives from Damascus where in the 12th century silk fabrics of a similar pattern were made.
Damaskeening is the process of ornamenting iron and steel with designs produced by inlaying or encrusting with another metal such as gold or silver, by etching and the like.
Dammar Gum is a naturally occurring gum obtained from coniferous trees that grow in the East Indies and Philippines. Dammar gum is soluble in turpentine and is employed in varnish and lacquers.
Dance is a rhythmic movement of the body usually performed to music.
Danegeld was a tax first levied by Ethelred II for the purpose of raising enough money to buy off the Danes and prevent their periodic invasions of England in the 10th century.
The Dark Ages were the five or six centuries following the fall of the west Roman Empire, after the civilisation of Rome, based on unity and inter-communication had been destroyed by repeated barbarian invasions.
A dark room is a specially darkened studio used for photographic work. As much of the material used in photography is sensitive to light, many operations must be conducted in darkness.
A Darlington Pair is an electronic circuit using two transistors with the collectors connected together and the emitter of the first directly coupled to the base of the second. This configuration gives very high gains equal to the gains of the two individual transistors multiplied together.
Data is information, especially that stored in a computer.
Daturine is the poisonous alkaloid found in the thorn-apple.
The Davis cup is a tennis tournament.
A day is the time taken for the earth to rotate once on its axis. Astronomically a day is reckoned to begin at noon; for civil purposes, at midnight.
Daylight Saving Time is a device for the better utilisation of daylight by a temporary abandonment of sun-time in summer. It was first suggested in 1907 by William Willett, and implemented in 1916 in order to procure economy in light and fuel as an Act which provided that all clocks be put forward one hour for a period of about 5.5 months during the summer in England. This emergency measure was perpetuated by an Act of 1925, and adopted by many other European countries.
dBM is an identifier meaning "decibels referred to one milliwatt," the common reference point for power levels in telecommunications circuits.
Ddt is an insecticide discovered in 1939 by Paul Muller.
De Haeretico Comburendo was a statute of 1401 against the Lollards. By it, a heretic convicted before a spiritual tribunal and refusing to recant was to be burned.
Decahydro-naphthalene is naphthalene which has been completely reduced by catalytic hydrogenation. It is a colourless liquid with a pleasant odour and the formulae C10H18 used as a solvent and cleaning-agent.
Decalin was a commercial name for Decahydro-naphthalene.
The decathlon is a 2 day Olympic athletic event.
Deceleration is the rate at which a moving body decreases in velocity.
The decibel is the unit of measurement of sound intensity.
In electronics, the decibel is a unit of measurement representing the logarithmic a ratio of two voltages, currents or power levels; used in telecommunications to express transmission loss or gain; defined as one-tenth of a Bel, hence the appropriate notation is dB, shown here.
The Declaration of Independence was made in 1776 by the 13 English colonies in North America breaking away from all allegiance to the British Crown. The Declaration was mainly the work of Thomas Jefferson. Already in December 1775 the Congress had declared itself independent of the English parliament and by this declaration had repudiated allegiance to the Crown.
The Declaration of Indulgence in 1687 was a proclamation by James II repealing all religious tests and penal laws against Roman Catholics and Dissenters. The Declaration was republished in 1688 and ordered to be read in the churches. Their refusal to do this led to the trial of the Seven Bishops, who were acquitted.
The Declaration of Paris in 1856 adopted with the Treaty of Paris to establish four principles of international law: 1) Privateering to be abolished; 2) the neutral flag might cover enemy goods except contraband of war; 3) neutral goods, except contraband of war, not to be subject to capture under an enemy's flag; 4) blockades, to be binding, must be effective, i.e. maintained by a sufficient force.
Strictly speaking, a decoy is either a tame or artificial duck, so placed as to lure wild ducks within gunshot range. The term is widely applied to any means by which a person or animal is lured into a trap.
In law, defamation is a false statement tending to expose another person to hatred, contempt or ridicule, or to injure him in his trade or profession. Mere insult is not sufficient.
The Defence of the Realm Acts (DORA) were a series of Acts passed during and after the Great War in Britain conferring on the King in Council the power to take extra-ordinary measures for the defence of the realm. Perhaps the most unpopular Act was the limitation of the times during which intoxicants could be sold, commonly known as the licensing hours and not relaxed until the 1990s.
Deimos is one of the two moons of mars.
A dekatron is a gas-filled cold-cathode electron tube, having a central anode and ten effective cathodes, used in electronic counting circuits.
A substance is deliquescent when it has an affinity for water strong enough to absorb it from the atmosphere in large quantities. Typically deliquescent salts are calcium chloride and ammonium nitrate.
see "Deliquescence"
Delta is the 4th letter of the Greek alphabet. In geography, a delta is an alluvial triangular deposit formed at diverging mouths of a river.
Delta Metal is a variety of brass containing 55 percent copper, 41 percent zinc and 4 percent various other metals.
Delta rays are a stream of electrons moving at a relatively low velocity.
A denaturant is a substance added to intoxicating liquids such as alcohol, so that while they are rendered unfit to drink are still usable in industry. However, the theory behind their use fails to appreciate the desperation of some alcoholics, and the drinking of methylated spirits despite being made more dangerous by the addition of toxic denaturants, is still just as widespread, but with even more injury occurring to those who consume it.
Density is the mass of a substance in relation to its volume, and usually expressed as the weight in grams of 1 cubic centimetre. Since volume enters into this dimension, and volume varies with temperature, it is essential that the temperature at which the measurement was taken is revealed when stating the density of a substance.
In architecture, a dentil is one of a series of small square projecting blocks in the moulding of a cornice. They were originally employed as a decorative representation of the beam-ends of a wooden roof, the term has been extended to apply to objects made of wood.
Dentistry is a branch of medical science concerned with the care of the teeth, and including the treatment of unsound teeth, the prevention of dental diseases and the manufacture of artificial teeth. Although practised in ancient Egypt, it was not until the 19th century that dentistry became a subject for serious scientific research and considered a branch of medicine.
Denudation is a geological term for the wearing away of the earth's surface by the various agents - rain, frost, rivers, glaciers and ocean waves, each agent exhibiting a different kind of erosion.
In old English law, deodand was a term denoting anything which had caused the death of a person, accidentally or otherwise, and was thereupon forfeited to the crown to be put to some good use.
A depilatory is a substance which has the power to remove hair other than by cutting it. The term is generally applied to cosmetic hair removers.
In geology, deposition is a term applied to the laying-down of material by the various agents, such as wind, rivers, lakes, oceans and glaciers, each deposit exhibiting distinct characteristics.
Derating is a scheme to encourage agriculture and industry by relieving them of a portion or the whole rates normally payable. the principle was introduced by Winston Churchill in the Budget of 1928 and incorporated in the Local Government (Derating) Act of 1929. The Act relieved agricultural land of the whole, and productive industry of three-quarters, of rates previously levied, and substituted therefor a lump sum government grant, distributed among the local authorities. The effect of derating was obscured by the subsequent industrial depression.
Dermatitis is a term applied to many kinds of inflammation of the skin.
A desiccator is an apparatus used mainly in the laboratory, by which substances can be thoroughly freed from water.
A desk is a flat or sloping table used for reading, writing or drawing, with or without legs. In the Middle Ages a plank was generally used.
The Devonian was the sixth geological period, 300,000,000 years ago. It marked the evolution of the insects and amphibians.
Dew is a precipitation in the form of moisture that collects on the ground after the temperature of the ground has fallen below the dew point temperature of the air in contact with the ground.
Dextrin is a sticky mixture of water-soluble products, an intermediate stage in the hydrolysis of starch into sugars. It was formerly marketed as an adhesive under the name of "British Gum".
A dialect is a characteristic manner of speech confined to a particular locality and differing, to a greater or lesser extent, from the standard speech of the country. The distinction between dialect and language is one of expediency rather than science.
Diallyl barbituric acid is a colourless crystalline organic compound used in medicine as a soporific.
Dialogue is a form of literature consisting of a conversation between two or more characters and so having considerable affinities with drama.
Diastase is a substance which occurs in saliva and in the secretions of the pancreas. It is an enzyme which has the power to break down starch with the formation of sugars.
Diathermy is a therapeutic treatment in which heat is produced in body tissues by passing high-frequency electric currents through them.
Diazo Compounds are a group of organic compounds characterised by the presence of the group -N2-. They are prepared by means of the diazo reaction, which consists in treating a primary aromatic amine with nitrous acid. Salts of this type are used in the production of dyestuffs.
A Dichroic mirror is a mirror consisting of a glass plate on which is deposited a very thin film of metal. It will transmit light of a particular colour, but reflects light of other colours.
A didjeridu is a musical wind instrument developed by the Australian aborigines.
Die-casting is a method of casting metals by forcing them under pressure into moulds of a strong and permanent character capable of repeated use. Die-casting is said to have originated with the advent of printing, which necessitated the production of sharply cast types in large numbers.
Dielectric is the name given to an electric insulating material.
Dietetics is the study of food in relation to the promotion and maintenance of health. Despite the attempts of some authors to claim it is a new science, it has been known and practised for centuries, and the term dietetics precedes the Second World War.
see "Veronal"
Diffusionism is the theory that human culture was spread by degrees by outward expansion from a single source, as opposed to the view that cultures are developed independently and are only diffused when a particular people develops a more or less permanent type of culture which is well in advance of that of neighbouring peoples and becomes impressed upon the latter.
Diflunisal is a drug used to treat mild to moderate pain and
osteoarthritis It has the possible side effects of: dizziness,
insomnia, headache, ringing in the ears, nausea, dyspepsia,
gastrointestinal pain, diarrhea, vomiting, constipation, excess wind,
rash and itching.
Digamma was an ancient Greek letter, which was already obsolete in classical times, and so called because its form resembled a double gamma. It was pronounced like an English w.
see "digestion"
Digestion is the process of absorbing and distributing substances from ingested food to the body.
Digitalis is a drug derived from foxglove that increases heart efficiency.
see "Tartaric Acid"
A dilatometer is an apparatus used to measure changes in volume of solids. The solid is placed in a glass bulb with a capillary tube, and the bulb and part of the tube are filled with a liquid which is without action on the solid. By observing the liquid's position in the tube, changes in the volume of the solid may be measured.
see "Theobromine"
see "Sulphonal"
Dimity is a strong cotton material with raised patterns, usually white, used for curtains and especially bed-curtains during the 18th and 19th centuries.
Dimorphism is a special case of polymorphism; the state when the same substance can appear in two different crystalline forms. Ice for example can exist as ordinary light ice, or if frozen below minus 20 degrees and subjected to high pressure forms dense ice which is heavier than water.
A dinghy is a small Indian river-boat. The term was adopted for the small row-boat attached to a larger vessel for general purposes and today is used to describe any small row-boat.
A diode is a thermionic valve with two electrodes, or a semi-conductor equivalent. It presents a high resistance one way around and a low resistance the other.
Diphenyl is an alternative name for Phenyl benzene.
Diphtheria is a disease produced by the Klebs-Loeffler bacillus. Diphtheria is unusual in that after infection it does not spread in the body, but the bacillus remains at the site of its primary invasion. This site may be the fauces in front of the throat, or the larynx. Very occasionally the bacillus gains access to a wound and gives rise to "wound diphtheria". In any case, the disease multiplies and produces a membrane which in the case of the laryngeal type may produce death by mechanical blockage of the air passage. The chief danger however lies in the toxins discharged by the bacillus which enter the blood system and affect the muscles in particular, giving rise to a danger of heart-attacks.
A dipole aerial is an aerial consisting of two straight conductors mounted in line, the connection being made to the two inner ends.
Dipsomania is the technical term for alcoholism, produced by taking large quantities of alcohol over a long period of time.
Dipyridamole is a coronary vasodilator drug used to reduce the frequency and
intensity of angina attacks and prevents blood clots after heart surgery.
A disinfectant is a substance applied to the outside of the body, or to non-living material in order to kill any micro-organisms which may be present.
Disopyramide is an antiarrhythmic drug used to correct heart rhythm
disorders which it does by delaying nerve impulses to the heart to
regulate the heartbeat.
In law, a Disorderly House is a house where persons meet for unlawful purposes, such as a brothel or gaming-house.
Displacement is the size of a ship as measured by the actual weight of water which it displaces when afloat.
Dissection is the process of cutting away and separating parts of a body, whereby its formation and the relationships of its parts can be observed.
In a car, the distributor distributes electrical pulses to the spark plugs.
A diuretic is a medicine which increases the flow of urine by acting on the kidneys either directly or secondarily through the blood or nervous system.
The term Dixie refers to the southern states of the USA.
The Doctor Wind is a prevailing daytime breeze which blows onto the island of Jamaica from the sea.
The dog days are the hottest part of the year in Europe, being part of July and August. Formerly the dog days were specifically the period during which Sirius, the dog-star, rises approximately with the sun.
The domesday book is a record of the survey conducted in England in 1086 by officials of William the conqueror in order to assess taxes etc.
Dominoes is a game played with 28 rectangular spotted tiles. It originated in Italy in the 18th century.
see "domesday book"
The Doppler effect is a change in observed wavelength due to relative motion between the source and observer.
see "Defence of the Realm Acts"
Down's syndrome is a chromosomal abnormality.
Dragon's Blood is a red resin obtained from the fruits of several East Indian trees. The material is a solid, soluble in alcohol and fatty oils, and used in the manufacture of furniture polishes, for staining marble and in some forms of printing.
The dram is a unit of the avoirdupois scale equivalent to 1.772 grams.
see "dram"
Draughts is a game played by two people on a board of 64 alternate black and white squares. Each player has twelve pieces, one set are black and the other red.
A dredger is a ship used for picking up rubbish from waterways and removing materials from beneath the surface of the water.
A drill is a machine for boring holes in rock, metal or wood etc. Drill bits were greatly improved from the invention in the 18th century of the twist drill, consisting of a rod of steel with a deep channel cut into it in a spiral, and the end ground off at an obtuse angle to give two cutting edges and a very short point.
Dropsy is an accumulation of serous fluid in the body cavities or tissues. Serum is normally exuded through the walls of the small blood-vessels, part of it being absorbed by the veins and lymphatic vessels and returned to the blood. Dropsy arises when the serum is not absorbed sufficiently or is exuded in abnormal quantities, and is therefore more a symptom of some other disturbance than a disease in itself.
Dry Ice is a commercial name for solidified carbon dioxide, often used as a coolant. It is called dry ice because as it melts, it gives off a gas rather than a liquid, and so appears dry.
In electrical terms, a dry joint is a soldered joint which, due to insufficient heating or lack of sufficient flux during the soldering operation, the solder has not adhered to the metals to be joined, thus producing a joint which is weak mechanically and of high electrical resistance.
Dry Rot is a name given to the fungus Merulius lacrymans which attacks wood in houses. The name derives from the dry appearance of the wood after decay.
A dry-dock is a dock from which the water may be emptied to allow of convenient and expeditious ship-repairs.
The dulcimer was a musical instrument consisting of a resonance-board over which wires were stretched, these being struck by hammers held by the performer.
The Duma was the lower House of the Russian Imperial Parliament. It was created in 1905 by the Constitution granted by Tsar Nicholas II, and replaced in 1917 by the Soviet system.
A dungeon is an underground prison, originally in the keep of a Norman castle.
Duralumin is an alloy of aluminium, copper and magnesium, with traces of other metals. Typically duralumin is comprised of 94.4 percent aluminium, 4.5 percent copper, 0.95 percent magnesium and 0.76 percent manganese. If properly tempered it has an extremely high tensile strength and is used in aircraft construction.
In law, duress is the unlawful constraint or compulsion of a person by physical action or threats.
The Dutch East India Company was a chartered company formed in 1595 and granted a monopoly of trade in the Pacific and Indian Ocean in 1602. It was dissolved in 1798 and its territories taken over by the Dutch Government.
The Dutch West India Company was a chartered company granted a monopoly of trade in the Atlantic Ocean with America and Africa by the Dutch Government in 1621.
DWIM is an acronym for Do What I Mean. It is a term used in artificial intelligence for computer self-correcting of errors.
A dye is a substance applied to material, usually a textile, for decorative purposes, to give it a colour different from that which it originally possessed.
A dyke (dike) is a ditch or earthworks. The term is most often applied to earthworks built to reclaim land from the sea or rivers.