crustacean, Old English crabba, from a general Germanic root (cf. Dutch krab, Old High German krebiz, German Krabbe, Old Norse krabbi "crab"), related to Low German krabben, Dutch krabelen "to scratch, claw," from PIE root *gerbh- "to scratch, carve" (see carve). The constellation name is attested in English from c.1000; the Crab Nebula (1868), however, is in Taurus, and is so called for its shape. French crabe (13c.) is from Dutch.
"fruit of the wild apple tree," c.1300, crabbe, perhaps from Scandinavian scrab, of obscure origin (cf. Swedish krabbäpple). The combination of "bad-tempered, combative" and "sour" in the two nouns crab naturally yielded a verb meaning of "to vex, irritate" (c.1400), later "to complain irritably, find fault" (c.1500). The noun meaning "sour person" is from 1570s.
c.1200, "to take, capture," from Anglo-French or Old North French cachier "catch, capture" (animals) (Old French chacier "hunt, pursue, drive (animals)," Modern French chasser "to hunt;" making it a doublet of chase (v.)), from Vulgar Latin *captiare "try to seize, chase" (also source of Spanish cazar, Italian cacciare), from Latin captare "to take, hold," frequentative of Latin capere "to take, hold" (see capable).
Senses in early Middle English also included "chase, hunt," which later went with chase (v.). Of infections from 1540s; of fire from 1734; of sleep, etc., from early 14c. Related: Catched (obsolete); catching; caught.
Meaning "act as a catcher in baseball" recorded from 1865. To catch on "apprehend" is 1884, American English colloquial. To catch (someone's) eye is first attested 1813, in Jane Austen. Catch as catch can first attested late 14c.
late 14c., "device to hold a latch of a door," also "a trap;" also "a fishing vessel," from catch (v.). Meaning "action of catching" attested from 1570s. Meaning "that which is caught or worth catching" (later especially of spouses) is from 1590s. Sense of "hidden cost, qualification, etc." is slang first recorded 1855 in P.T. Barnum.