WordNet (r) 3.0 (2006):

riboflavin
    n 1: a B vitamin that prevents skin lesions and weight loss
         [syn: vitamin B2, vitamin G, riboflavin,
         lactoflavin, ovoflavin, hepatoflavin]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "riboflavin":
   adermin, aneurin, antiberi-beri factor, ascorbic acid, axerophthol,
   biotin, carotene, cholecalciferol, choline, cobalamin,
   cryptoxanthin, cyanocobalamin, ergocalciferol, folic acid,
   hepatoflavin, inositol, lactoflavin, menadione, naphthoquinone,
   niacin, nicotinic acid, ovoflavin, pyridoxine, tocopherol, vitamin,
   vitamin B, vitamin Bc, vitamin D, vitamin G, vitamin H, vitamin K,
   vitamin M