Origin and history of trigger

1849, in a South African context, "a stage of a journey by ox wagon;" from Afrikaans trek, "a journey or migration; distance between one place and the next; action of drawing" a vehicle, as an ox; from Dutch trekken "to march, journey," originally "to draw, pull," from Middle Dutch trecken, which probably is related to the source of track (n.).

Historically, especially in reference to the Groot Trek (1835 and after) of more than 10,000 Boers, who, discontented with the English colonial authorities, left Cape Colony and went north and north-east. In general use in English as a noun, "long journey or toilsome expedition," by 1941.

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).