Entry 1 sense Webster, 1913 Leucosoid /(-soid)/ · Leu·co·soid · IPA 01 a. Like or pertaining to the Leucosoidea, a tribe of marine crabs including the box crab or Calappa. 1. Like or pertaining to the Leucosoidea, a tribe of marine crabs including the box crab or Calappa.(Zool.)