Word Origin & History
O.E. crabba, from a general Gmc. root (cf. Low Ger. krabben "to scratch, claw"). The constellation name is attested in Eng. from c.1000; the Crab Nebula (1868), however, is in Taurus, and is so called for its shape. Crab "fruit of the wild apple tree" (early 15c.) may be from unrelated Scandinavian scrab,
of obscure origin. The combination of "bad-tempered, combative" and "sour" in the two words naturally yielded a meaning of "complain irritably," which is pre-1400. Crabgrass is c.1600, originally a marine grass of salt marshes; modern meaning is from 1743.