adj., adv., n., & v.
adj. 1 a consisting of two usu. equal parts or things; twofold. b consisting of two identical parts. 2 twice as much or many (double the amount; double the number; double thickness). 3 having twice the usual size, quantity, strength, etc. (double whisky). 4 designed for two people (double bed). 5 a having some part double. b (of a flower) having more than one circle of petals. c (of a domino) having the same number of pips on each half. 6 having two different roles or interpretations, esp. implying confusion or deceit (double meaning; leads a double life). 7 Mus. lower in pitch by an octave (double bassoon).
adv. 1 at or to twice the amount etc. (counts double). 2 two together (sleep double).
n. 1 a a double quantity or thing; twice as much or many. b colloq. a double measure of spirits. 2 a a counterpart of a person or thing; a person who looks exactly like another. b an understudy. c a wraith. 3 (in pl.) Sport (in lawn tennis) a game between two pairs of players. 4 Sport a pair of victories over the same team, a pair of championships at the same game, etc. 5 a system of betting in which the winnings and stake from the first bet are transferred to a second. 6 Bridge the doubling of an opponent's bid. 7 Darts a hit on the narrow ring enclosed by the two outer circles of a dartboard, scoring double. 8 a sharp turn, esp. of the tracks of a hunted animal, or the course of a river.
v. 1 tr. & intr. make or become twice as much or many; increase twofold; multiply by two. 2 tr. amount to twice as much as. 3 a tr. fold or bend (paper, cloth, etc.) over on itself. b intr. become folded. 4 a tr. (of an actor) play (two parts) in the same piece. b intr. (often foll. by for) be understudy etc. 5 intr. (usu. foll. by as) play a twofold role. 6 intr. turn sharply in flight or pursuit; take a tortuous course. 7 tr. Naut. sail round (a headland). 8 tr. Bridge make a call increasing the value of the points to be won or lost on (an opponent's bid). 9 Mus. a intr. (often foll. by on) play two or more musical instruments (the clarinettist doubles on tenor sax). b tr. add the same note in a higher or lower octave to (a note). 10 tr. clench (a fist). 11 intr. move at twice the usual speed; run. 12 Billiards a intr. rebound. b tr. cause to rebound. at the double running, hurrying. bent double folded, stooping. double acrostic see ACROSTIC. double agent one who spies simultaneously for two rival countries etc. double axe an axe with two blades. double back take a new direction opposite to the previous one. double-banking 1 double-parking. 2 Austral. & NZ riding two on a horse etc. double-barrelled 1 (of a gun) having two barrels. 2 Brit. (of a surname) having two parts joined by a hyphen. 3 twofold. double-bass 1 the largest and lowest-pitched instrument of the violin family. 2 its player. double bill a programme with two principal items. double bind a dilemma. double-blind adj. (of a test or experiment) in which neither the tester nor the subject has knowledge of identities etc. that might lead to bias.
n. such a test or experiment. double bluff an action or statement intended to appear as a bluff, but in fact genuine. double boiler a saucepan with a detachable upper compartment heated by boiling water in the lower one. double bond Chem. a pair of bonds between two atoms in a molecule. double-book accept two reservations simultaneously for (the same seat, room, etc.). double-breasted (of a coat etc.) having two fronts overlapping across the body. double-check verify twice or in two ways. double chin a chin with a fold of loose flesh below it. double-chinned having a double chin. double concerto a concerto for two solo instruments. double cream thick cream with a high fat-content. double-cross v.tr. deceive or betray (a person one is supposedly helping).
n. an act of doing this. double-crosser a person who double-crosses. double dagger Printing = double obelus. double-dealer a deceiver. double-dealing n. deceit, esp. in business.
adj. deceitful; practising deceit. double-decker 1 esp. Brit. a bus having an upper and lower deck. 2 colloq. anything consisting of two layers. double-declutch see DECLUTCH. double decomposition Chem. a chemical reaction involving exchange of radicals between two reactants: also called METATHESIS. double density Computing designating a storage device, esp. a disk, having twice the basic capacity. double dummy Bridge play with two hands exposed, allowing every card to be located. double Dutch Brit. colloq. incomprehensible talk. double-dyed deeply affected with guilt. double eagle 1 a figure of a two-headed eagle. 2 US Golf = ALBATROSS. 3 US a coin worth twenty dollars. double-edged 1 having two functions or (often contradictory) applications. 2 (of a knife etc.) having two cutting-edges. double entry a system of bookkeeping in which each transaction is entered as a debit in one account and a credit in another. double exposure Photog. the accidental or deliberate repeated exposure of a plate, film, etc. double-faced 1 insincere. 2 (of a fabric or material) finished on both sides so that either may be used as the right side. double fault (in lawn tennis) two consecutive faults in serving. double feature a cinema programme with two full-length films. double figures the numbers from 10 to 99. double first Brit. 1 first-class honours in two subjects or examinations at a university. 2 a person achieving this. double-fronted (of a house) with principal windows on either side of the front door. double-ganger = DOPPELGNGER. double glazing 1 a window consisting of two layers of glass with a space between them, designed to reduce loss of heat and exclude noise. 2 the provision of this. double Gloucester a kind of hard cheese orig. made in Gloucestershire. double header 1 a train pulled by two locomotives coupled together. 2 US two games etc. in succession between the same opponents. 3 Austral. colloq. a coin with a head on both sides. double helix a pair of parallel helices with a common axis, esp. in the structure of the DNA molecule. double-jointed having joints that allow unusual bending of the fingers, limbs, etc. double-lock lock by a double turn of the key. double negative Gram. a negative statement containing two negative elements (e.g. didn't say nothing). °Considered ungrammatical in standard English. double obelus (or obelisk) Printing a sign used to introduce a reference. double or quits a gamble to decide whether a player's loss or debt be doubled or cancelled. double-park park (a vehicle) alongside one that is already parked at the roadside. double play Baseball putting out two runners. double pneumonia pneumonia affecting both lungs. double-quick very quick or quickly. double refraction Optics refraction forming two separate rays from a single incident ray. double rhyme a rhyme including two syllables. double salt Chem. a salt composed of two simple salts and having different crystal properties from either. double saucepan Brit. = double boiler. double shuffle Dancing a shuffle executed twice with one foot and then twice with the other. double standard 1 a rule or principle applied more strictly to some people than to others (or to oneself). 2 bimetallism. double star two stars actually or apparently very close together. double-stopping Mus. the sounding of two strings at once on a violin etc. double take a delayed reaction to a situation etc. immediately after one's first reaction. double-talk verbal expression that is (usu. deliberately) ambiguous or misleading. double-think the mental capacity to accept contrary opinions or beliefs at the same time esp. as a result of political indoctrination. double time 1 payment of an employee at twice the normal rate. 2 Mil. the regulation running-pace. double-tonguing rapid articulation in playing a wind instrument. double top Darts a score of double twenty. double up 1 a bend or curl up. b cause to do this, esp. by a blow. 2 be overcome with pain or laughter. 3 share or assign to a room, quarters, etc., with another or others. 4 fold or become folded. 5 use winnings from a bet as stake for another. doubler n. doubly adv.
[ ME f. OF doble, duble (n.), dobler, dubler (v.) f. L duplus DUPLE ]