Zool. [mod.L. (Da Costa 1776), f. Gr. τρίδακν-ος eaten at three bites, f. τρι-, TRI- + δάκν-ειν to bite.] A genus of bivalve mollusks, including the Tridacna gigas or Giant Clam, the largest bivalve shell known. Also attrib.
1776. Da Costa, Conchol., 294. A Tridacna, the Bason Conch or Clamp.
1860. Wraxall, Life in Sea, xiv. 299. The giant Tridacna, which is five feet broad, forms entire submarine banks.
1904. Athenæum, 24 Sept., 419/1. In graves at Rubiana were found rings of tridacna shell and other objects of the same material carved in a fretwork design.
So † Tridacnan a. Obs. rare–0.
1623. Cockeram, Tridacnan, any thing that is so big that must be cut in three pieces, or morsels, ere it can be eat.
