any one of numerous species of marine bivalve mollusks of the genus pecten and allied genera of the family pectinidae. the shell is usually radially ribbed, and the edge is therefore often undulated in a characteristic manner. the large adductor muscle of some the species is much used as food. one species (vola jacobaeus) occurs on the coast of palestine, and its shell was formerly worn by pilgrims as a mark that they had been to the holy land. called also fan shell. see pecten, 2.-one of series of segments of circles joined at their extremities, forming a border like the edge or surface of a scallop shell.-one of the shells of a scallop; also, a dish resembling a scallop shell.-to mark or cut the edge or border of into segments of circles, like the edge or surface of a scallop shell. see scallop, n., 2.-to bake in scallop shells or dishes; to prepare with crumbs of bread or cracker, and bake. see scalloped oysters, below.