Entry 1 sense Webster, 1913 ovoflavin · IPA 01 n. An uncommon name for riboflavin, also called vitamin B2. 1. An uncommon name for riboflavin, also called vitamin B2. Also: vitamin B2 See: riboflavin Syn. vitamin B2, vitamin G, riboflavin, lactoflavin, lactoflavine, hepatoflavin.