rack¹ / rak/ • n. 1. a framework, typically with rails, bars, hooks, or pegs, for holding or storing things: a spice rack a magazine rack. ∎  an overhead shelf on a bus, train, or plane for stowing luggage. ∎  a vertically barred frame or wagon for holding animal fodder: a hay rack. ∎  a lift used for elevating and repairing motor vehicles. ∎  a set of antlers. ∎ vulgar slang a woman's breasts: Arnie's woman is kinda bossy, but she's got a nice rack. ∎ inf. a bed.2. a cogged or toothed bar or rail engaging with a wheel or pinion, or using pegs to adjust the position of something: a steering rack.3. (the rack) hist. an instrument of torture consisting of a frame on which the victim was stretched by turning rollers to which the wrists and ankles were tied.4. a triangular structure for positioning the balls in pool. Compare with frame (sense 5). ∎  the triangular arrangement of balls set up for the beginning of a game of pool.5. a digital effects unit for a guitar or other instrument, typically giving many different sounds.• v. [tr.] 1. (also wrack) (often be racked) cause extreme physical or mental pain to; subject to extreme stress: he was racked with guilt. ∎ hist. torture (someone) on the rack.2. [tr.] place in or on a rack: the shoes were racked neatly beneath the dresses. ∎  [tr.] put (pool balls) in a rack.3. chiefly archaic raise (rent) above a fair or normal amount. PHRASES: go to rack (or wrack) and ruin gradually deteriorate in condition because of neglect: fall into disrepair.off the rack (of clothes) ready-made rather than made to order.on the rack suffering intense distress or strain.rack (or wrack) one's brains (or brain) make a great effort to think of or remember something.PHRASAL VERBS: rack something up accumulate or achieve something, typically a score or amount: Japan is racking up record trade surpluses with the U.S.rack² • n. a horse's gait in which both hoofs on either side in turn are lifted almost simultaneously, and all four hoofs are off the ground together at certain moments.• v. [intr.] (of a horse) move with such a gait.rack³ • n. a large cut of meat, typically lamb, that includes the front ribs. rack⁴ • v. [tr.] draw off (wine, beer, etc.) from the sediment in the barrel: the wine is racked off into large oak casks. rack⁵ (also wrack) • n. a mass of high, thick, fast-moving clouds: there was a thin moon, a rack of cloud.• v. [intr.] archaic (of a cloud) be driven before the wind.

rack1 an instrument of torture consisting of a frame on which the victim was stretched by turning rollers to which the wrists and ankles were tied; it is first recorded in English in Caxton' translation of Reynard the Fox (1481), and is sometimes found in the expression come rack, come rope.
rack one's brains make a great effort to think of or remember something.
rack rent an extortionate or very high rent; in legal usage, a rent equal to or close to the annual value of the property. Recorded from the early 17th century, the expression was particularly associated with the Protestant Ascendancy in Ireland by the publication in 1800 of Maria Edgeworth' novel Castle Rackrent.

rack3 instrument of torture in the form of a frame with a roller at each end. XV. prob. spec. use of RACK2.
So vb. stretch the joints of XV; in various transf. and fig. uses XVI. — MLG., MDu. racken, also recken = OE. reċċan, OS. rekkian, OHG. recchan (G. recken), ON. rekja, Goth. -rakjan stretch; rel. to L. regere DIRECT.

rack1
A. †shock, collision XIII;

B. mass of driven cloud XIV. prob. of Scand. orig.; cf. Norw. and Sw. dial. rak (Sw. uvak, Da. vrag) wreck, wreckage, refuse, f. reka drive; the identity of A and B is not certain.

rack2 go to rack and ruin gradually deteriorate in condition because of neglect: fall into disrepair; rack here is a variant (recorded from the late 16th century) of wrack ‘damage, disaster’.