Online Etymology Dictionary

wrench (n.): O.E. wrenc "a twisting, artifice, trick;" see wrench (v.). The meaning "tool with jaws for turning" is first recorded 1794.
wrench (v.): O.E. wrencan "to twist," from P.Gmc. *wrankijanan (cf. O.H.G. renken, Ger. renken "to twist, wrench," O.E. wringan "to wring"), from PIE *wreng- "to turn" (cf. Skt. vrnakti "turns, twists," Lith. rengtis "to grow crooked, to writhe"), nasalized variant of *werg- "to turn" (cf. L. vergere "to turn, tend toward"), from base *wer- "to turn, bend" (see versus).
Allen: masc. proper name, variant of Alan (q.v.). In ref. to wrench, key, screw, etc. with hexagonal socket or head, 1930, from the Allen Manufacturing Company of Hartford, Connecticut, U.S.
extortion: c.1300, from L. extorquere "wrench out, wrest away," from ex- "out" + torquere "to twist" (see thwart).
wrest: O.E. wræstan "to twist, wrench," from P.Gmc. *wraistijanan (cf. O.N. reista "to bend, twist"), derivative of *wrig-, *wreik- "to turn" (see wry). Meaning "to pull, detach" (something) is recorded from c.1300. Meaning "to take by force" (in ref. to power, authority, etc.) is attested from 1426.
convulse (v.): 1640s, trans.; 1680s, intrans.; from L. convuls-, pp. stem of convellere (trans. only) "to pull away, to pull this way and that, wrench," hence "to weaken, overthrow, destroy" (see convulsion). Related: Convulsed (1630s); convulsing (1829).
wrinkle (n.): 1387 (in wrinkling), probably from stem of O.E. gewrinclod "wrinkled, crooked, winding," pp. of gewrinclian "to wind, crease," from perfective prefix ge- + -wrinclian "to wind," from P.Gmc. *wrankjan (see wrench (v.)). Meaning "defect, problem" first recorded 1643; that of "idea, device, notion" (especially a new one) is from 1817. The verb is attested from 1528.
socket: c.1300, "spearhead" (originally one shaped like a plowshare), from Anglo-Fr. soket "spearhead" (c.1260), dim. of O.Fr. soc "plowshare," from V.L. *soccus, probably from a Gaulish source, cf. Welsh swch "plowshare," Middle Irish soc "plowshare," prop. "hog's snout," cognate with L. sus "swine;" see sow (n.) "female pig." Meaning "hollow part or piece for receiving and holding something" first recorded 1448; anatomical sense is from 1601; domestic electrical sense first recorded 1885. Socket wrench is attested from 1905.
span (v.): O.E. spannen "to clasp, fasten, stretch, span," from P.Gmc. *spanwanan (cf. O.N. spenna, O.Fris. spanna, M.Du. spannen, O.H.G. spannan, Ger. spannen), from PIE base *(s)pen- "to draw, stretch, spin" (cf. L. pendere "to hang, to cause to hang," pondus "weight" (the weight of a thing measured by how much it stretches a cord), pensare "to weigh, consider;" Gk. ponein "to toil;" Lith. spendziu "lay a snare;" O.C.S. peti "stretch, strain," pato "fetter," pina "I span;" O.E. spinnan "to spin;" for other cognates, see spin). The meaning "to encircle with the hand(s)" is from 1781; in the sense of "to form an arch over (something)" it is first recorded 1633. Spanner (1639), the British name for the wrench, is from Ger., originally a tool for winding the spring of a wheel-lock firearm.
monkey: 1530, likely from an unrecorded M.L.G. *moneke or M.Du. *monnekijn, a colloquial word for "monkey," originally a dim. of some Romanic word, cf. Fr. monne (16c.), O.It. monna, Sp. mona. In a 1498 Low Ger. version of the popular medieval beast story "Roman de Renart" ("Reynard the Fox"), Moneke is the name given to the son of Martin the Ape. The O.Fr. form of the name is Monequin (recorded as Monnekin in a 14c. version from Hainault), which could be a dim. of some personal name, or it could be from the general Romanic word, which may be ult. from Arabic maimun "monkey," lit. "auspicious," a euphemistic usage because the sight of apes was held by the Arabs to be unlucky. The word would have been influenced in It. by folk-etymology from monna "woman," a contraction of ma donna "my lady." Monkey has been used affectionately for "child" since 1605. As a type of modern popular dance, it is attested from 1964. Monkeyshines is first recorded 1832, Amer.Eng.; monkey business attested from 1883. Monkey suit "fancy uniform" is from 1886. Monkey wrench is attested from 1858; its fig. sense of "Something that obstructs operations" is from the notion of one getting jammed in the gears of machinery (cf. spanner in the works). To make a monkey of someone is attested from 1900. To have a monkey on one's back "be addicted" is 1930s narcotics slang, though the same phrase in the 1860s meant "to be angry." There is a story in the Sinbad cycle about a tormenting ape-like creature that mounts a man's shoulders and won't get off, which may be the root of the term. In 1890s British slang, to have a monkey up the chimney meant "to have a mortgage on one's house." The three wise monkeys ("see no evil," etc.) are attested from 1926.