parasitic blood-sucking arachnid animal, Old English ticia, from West Germanic *tik- (source also of Middle Dutch teke, Dutch teek, Old High German zecho, German Zecke "tick"), of unknown origin, perhaps from PIE *deigh- "insect." French tique (mid-15c.), Italian zecca are Germanic loan-words.
mid-15c., "light touch or tap," probably from tick (v.) and cognate with Dutch tik, Middle High German zic, and perhaps echoic. Meaning "sound made by a clock" is probably first recorded 1540s; tick-tock as the sound of a clock is recorded from 1845.
"credit," 1640s, shortening of ticket (n.).
early 13c., "to touch or pat," perhaps from an Old English verb corresponding to tick (n.2), and perhaps ultimately echoic. Compare Old High German zeckon "to pluck," Dutch tikken "to pat," Norwegian tikke "touch lightly." Meaning "make a ticking sound" is from 1721. Related: Ticked; ticking.
To tick (someone) off is from 1915, originally "to reprimand, scold." The verbal phrase tick off was in use in several senses at the time: as what a telegraph instrument does when it types out a message (1873), as what a clock does in marking the passage of time (1777), to enumerate on one's fingers (1899), and in accountancy, etc., "make a mark beside an item on a sheet with a pencil, etc.," often indicating a sale (by 1881, from tick (n.2) in sense "small mark or dot"). This last might be the direct source of the phrase, perhaps via World War I military bureaucratic sense of being marked off from a list as "dismissed" or "ineligible." Meaning "to annoy" is recorded by 1971.
1821, "something that ticks," agent noun from tick (v.); slang meaning "heart" first recorded 1930. Ticker tape (1891) is from ticker "telegraphic device for recording stock market quotations, etc." (1883).
"children's game," 1738 (in reference to "Queen Mary's reign"), perhaps a variation of Scottish tig "touch, tap" (1721), probably an alteration of Middle English tek "touch, tap" (see tick (n.2)). Baseball sense is from 1912. It's not an acronym and doesn't stand for anything.
c. 1300 (implied in tickling) "to touch lightly so as to cause a peculiar and uneasy or thrilling sensation in the nerves," of uncertain origin, possibly a frequentative form of tick (v.) in its older sense of "to touch." Some suggest a metathesis of Middle English kittle, which is from a shared Germanic word for "to tickle," but tickle is attested earlier. The Old English form was tinclian.
Meaning "to excite agreeably" (late 14c.) is a translation of Latin titillare. Meaning "to poke or touch so as to excite laughter" is from early 15c.; figurative sense of "to excite, amuse" is attested from 1680s. The noun is recorded from 1801. To tickle (one's) fancy is from 1640s. Related: Tickler.
children's three-in-a-row game with Xs and Os, so called by 1892, earlier tit-tat-toe (by 1852, in reminiscences of earlier years), also called noughts and crosses (1852), also oughts and crosses. Probably from the sound of the pencil on the slate with which it originally was played by schoolboys. Also the name of a children's counting rhyme played on slate (also originally tit-tat-toe, by 1842), and compare tick-tack (1580s), a form of backgammon, possibly from French trictrac, perhaps imitative of the sound of tiles on the board.
