biotin(n = noun.substance) vitamin h - a B vitamin that aids in body growth;
is a kind of b, b-complex vitamin, b complex, b vitamin, vitamin b, vitamin b complex

   a B vitamin (C10H16N2O3S) that aids in body growth; -- called also vitamin H and coenzyme R. It functions as a coenzyme in many carboxylation reactions.
"Biotin binds tightly to the substance avidin, found in raw egg-whites. Rats or chick on a diet high in raw egg-white may develop skin lesions and retarded growth, which can be prevented by adding biotin to the diet." [WordNet 1.5]

biotin, n. a vitamin of the B complex, found in egg yolk, liver, and yeast, and involved in the metabolism of carbohydrates, fats, and proteins.

Etymology:
G f. Gk bios life + -IN