crabby adj.

popular name for a stalk-eyed, short-tailed, ten-legged crustacean, Old English crabba, from a general Germanic root (compare 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). French crabe (13c.) is from Germanic, probably Old Norse. 

The zodiac constellation name is attested in English from c. 1000; the Crab Nebula (1840), however, is in Taurus, the result of the supernova of 1054, and is so called for its shape. Crab stick "white fish meat dyed to resemble crab and pressed into a stick shape" is by mid-1950s. To catch a crab "fall or be thrown due to a mistake in rowing" is from 1785. The crab-louse (1540s), commonly found in pubic hair, is so called for its shape and appearance. Short form crab for this is from 1840; related: Crabs.

adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.

late 14c., "peevish, angry, ill-tempered, spiteful," also "vicious, wicked, perverse," from crab (n.1), from the crab's combative disposition; mid-15c. as "moving backwards" and in reference to crookedness. Of taste "bitter, harsh," late 14c., from crab (n.2). Related: Crabbedly; crabbedness.