Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or from cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791).

In Middle English and after often spelled -ick, -ike, -ique. Variant forms in -ick (critick, ethick) were common in early Modern English and survived in English dictionaries into early 19c. This spelling was supported by Johnson but opposed by Webster, who prevailed.

1680s, "the science of sound," from acoustic; also see -ics. The meaning "acoustic properties" of a building, etc., is attested from 1885.

1859, "acrobatic performances or feats," from acrobatic; also see -ics. Also acrobatism (1864). Acrobacy (1918, from French acrobatie) sometimes was used. Figurative use is attested by 1915.

method of exercise and a fad in early 1980s, American English, coined 1968 by U.S. physician Kenneth H. Cooper (b. 1931), from aerobic (also see -ics) on the notion of activities which require modest oxygen intake and thus can be maintained.

science of gliding, 1907, Modern Latin coinage by English engineer Frederick W. Lanchester (1868-1946) from Greek aēr (genitive aeros) "air" (see air (n.1)) + stem of donein "to shake, drive about," for which Beekes gives no etymology. Also see -ics.

1824, "art of aerial navigation by means of a balloon," from aeronautic (1784), from French aéronautique, from aéro- (see aero-) + nautique "of ships," from Latin nauticus, from Greek nautikos "pertaining to sailing" (see nautical). Also see -ics. Aeronaut "balloonist" is from 1784, from French aéronaute.

1803, from aesthetic (adj.); also see -ics.

"the division of logic which distinguishes good from bad arguments," 1590s, from Latin analytica from Greek analytika, from stem of analyein "unloose, release, set free," from ana "up, back, throughout" (see ana-) + lysis "a loosening," from lyein "to unfasten" (from PIE root *leu- "to loosen, divide, cut apart"); also see -ics. Ta Analytika was the name of Aristotle's treatises on logic.

"branch of theology which defends Christian belief," 1733, from apologetic (which is attested from early 15c. as a noun meaning "formal defense"); also see -ics.

"the art of traveling in outer space," 1929; see astronaut + -ics.