Entry 1 sense Webster, 1913 Aspidobranchia · As·pi·do·bran·chi·a · IPA 01 n. pl. A group of Gastropoda, with limpetlike shells, including the abalone shells and keyhole limpets. 1. A group of Gastropoda, with limpetlike shells, including the abalone shells and keyhole limpets.(Zool.)