Entry 1 sense Webster, 1913 octamerous /(ocr/k*tăm"ẽr*ŭs)/ · oc·tam·er·ous · IPA 01 a. Having the parts in eights; as, an octamerous flower; octamerous mesenteries in polyps. 1. Having the parts in eights; as, an octamerous flower; octamerous mesenteries in polyps.(Biol.)