Entry 1 sense Webster, 1913 Etiology /ētˌ-ē-äl'-əj-ē/ · E·ti·ol·o·gy · IPA /ˌiːtiːˈɑlədʒiː/ 01 n. The science of causes. Same as �tiology. 1. The science of causes. Same as �tiology. See: tiology