n. In anatomy, the proximal element of Meckel's cartilage, in any way distinguished from the rest of the mandibular arch.n. In ichthyology, one of the Weberian ossicles which form a chain between the air-bladder and the auditory apparatus in the skull of plectospondylous and nematognathous fishes. It is homologous with the hemapophysis of the third one of the coalesced anterior vertebræ.n. In rotifers, one of the paired calcareous structures within the pharynx.n. [capitalized] In conchology, a genus of pearl-oysters of the family Avieulidæ, founded by Lamarck in 1799; the hammer-shells.n. Same as war-hammer.