Etymology
1. 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" (c.1420) may be from unrelated Scand.
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, though
crabby in this sense is Amer.Eng. 18c.
Crabgrass is 1597, originally a marine grass of salt marshes; modern meaning is from 1743.
2. From Middle English crabbe, from Old English crabba (“crab; crayfish; cancer”), from Proto-West Germanic *krabbō, from Proto-Germanic *krabbô, from *krabbōną (“to scratch”), from Proto-Indo-European *grobʰeh₂yéti (“to scratch”), a metathesised o-grade of *gerbʰ- (“to carve, scratch”). More at carve.
3. Cognates
4. See also Dutch krab, Low German Krabb, Danish krabbe, Swedish krabba.
5. Further cognates with frequentative-infix are Saterland Frisian krabbelje (“to creep, crawl”), Dutch krabbelen (“to scratch”) and German krabbeln (“to crawl”). Possibly related to English creep and Swedish krypa (“to creep, crawl”) etc.
6. Other origins have also been suggested, see Ancient Greek κάραβος (kárabos) (regarding the possibility of a substrate origin) and Persian خرچنگ (regarding possible ideophonic origin); compare also Old Armenian քարբ (kʻarb), German Krebs. See: Frisian, Saterlandic 'krabbelje', Dutch '
krabbelen', German, old spelling '
krabbeln', English '
creep', Swedish '
krypa'.