noun
: any of numerous crabs living between the tidemarks: as
a. : green crab
b. : a spider crab of the genus Libinia common along the eastern coast of the United States
c. : any of several grapsoid crabs of the western coast of No. America — usually used with a qualifying term; see purple shore crab , striped shore crab , yellow shore crab
d. : a common So. Australian grapsoid crab ( Leptograpsus variegatus )