Entry 1 sense Webster, 1913 endozoic /(ĕn`dō̇*zō"ĭk)/ · en·do·zo·ic · IPA 01 adj. Living within a living animal, usually as a parasite; as, endozoic worms. Contrasted with epizoic. 1. Living within a living animal, usually as a parasite; as, endozoic worms. Contrasted with epizoic. Syn. entozoic, entozoan.