Entry 1 sense Webster, 1913 Ai /ā′ī′/ · A·i · IPA /ˈɑ.i/ 01 n. The three-toed sloth (Bradypus tridactylus) of South America. See Sloth. pl. Ais 1. The three-toed sloth (Bradypus tridactylus) of South America. See Sloth.(Zool.) See: Sloth