"disentangle, disengage, set free," 1610s, from Latin extricatus, past participle of extricare "disentangle," figuratively "clear up, unravel," perhaps from ex "out of" (see ex-) + tricae (plural) "perplexities, hindrances," which is of unknown origin. Related: Extricated; extricating.

c. 1600, "state of being complex;" 1610s, "an intricate situation or condition," from intricate (adj.) + -cy. Related: Intricacies.

1610s, "to trick, deceive, cheat," from French intriguer (16c.), from Italian intrigare "to plot, meddle; perplex, puzzle," from Latin intricare "to entangle, perplex, embarrass" (see intricate).

Meaning "to plot or scheme" is recorded by 1714. That of "to excite curiosity" is from 1894 (OED calls this use "A modern gallicism"). It also could mean "carry on a clandestine or illicit sexual relationship" (1650s). The word appears earlier in English as entriken "entangle, ensnare; involve in perplexity, embarrass" (late 14c.), from Old French entrique or directly from the Latin verb. Related: Intrigued; intriguer; intriguing. Dutch intrigueren, German intriguiren are from French.

early 15c., "a cheat, a mean ruse, crafty or fraudulent device," from Old North French trique "a deceit, treachery, cheating," from trikier "to deceive, to cheat," variant of Old French trichier "to cheat, trick, deceive," a word of uncertain origin.

OED (1989) cites scholars of French who refer it to Vulgar Latin *triccare, from Latin tricari "be evasive, shuffle," from tricæ "trifles, nonsense, a tangle of difficulties" (as in extricate, intricate), itself of uncertain etymology.

Others suggest a Middle Dutch origin or influence for the French word and point to Dutch trek "a pull, a tug" in a secondary sense "a trick." Also compare trigger, with which its senses have been entangled and its forms confused.

By 1570s as "clever device or expedient;" the meaning "a roguish prank" is recorded from 1580s. Formerly also "small article, toy, knick-knack" (1550s). To play tricks is by 1550s, formerly also often put tricks (1620s). 

In card-playing, "cards collectively which have been played in one round," by 1590s (the taking of them often determines the winner of the game). Hence, probably, miss a trick "fail to take advantage of opportunity" (1889, probably extended from whist, where it is attested by 1872).

It is attested by c. 1600 as "feat or exhibition of skill to surprise or amuse." The sense of "art of doing something" is attested by 1610s. One's old tricks "bad habits" is by 1580s. Tricks of the trade "expediences, artifices, and dodges of a craft or business" is by 1895. Slang greeting how's tricks? is attested by 1882. To do the trick "accomplish one's purpose" is by 1812 in slang.

Trick-or-treat as a children's Halloween pastime is recorded from 1926 in Canada, as tricks or treats by 1917. Trick question, one designed to elicit more than it seems to ask, is from 1907. Also compare hat trick.

The meaning "prostitute's client" is first attested 1915; earlier it was U.S. slang for "a robbery" (by 1865).

Proto-Indo-European root meaning "in."

It might form all or part of: and; atoll; dysentery; embargo; embarrass; embryo; empire; employ; en- (1) "in; into;" en- (2) "near, at, in, on, within;" enclave; endo-; enema; engine; enoptomancy; enter; enteric; enteritis; entero-; entice; ento-; entrails; envoy; envy; episode; esoteric; imbroglio; immolate; immure; impede; impend; impetus; important; impostor; impresario; impromptu; in; in- (2) "into, in, on, upon;" inchoate; incite; increase; inculcate; incumbent; industry; indigence; inflict; ingenuous; ingest; inly; inmost; inn; innate; inner; innuendo; inoculate; insignia; instant; intaglio; inter-; interim; interior; intern; internal; intestine; intimate (adj.) "closely acquainted, very familiar;" intra-; intricate; intrinsic; intro-; introduce; introduction; introit; introspect; invert; mesentery.

It might also be the source of: Sanskrit antara- "interior;" Greek en "in," eis "into," endon "within;" Latin in "in, into," intro "inward," intra "inside, within;" Old Irish in, Welsh yn, Old Church Slavonic on-, Old English in "in, into," inne "within, inside."