Meaning of antivitamin

an•ti•vi•ta•min

Pronunciation: (an"tē-vī'tu-min, an"tī- or, Brit., -vit'u-min), [key]
— n. Biochem.
  1. any substance that interferes with the action of a vitamin.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.