vitamin b

from WordNet (r) 3.0 (2006)

vitamin B
    n 1: originally thought to be a single vitamin but now separated
         into several B vitamins [syn: {B-complex vitamin}, {B
         complex}, {vitamin B complex}, {vitamin B}, {B vitamin},
         {B}]

from The Collaborative International Dictionary of English v.0.48

vitamin B \vitamin B\ n.
   a group of water-soluble vitamins originally thought to be a
   single vitamin but now separated into several B vitamins.

   Syn: B-complex vitamin, B complex, vitamin B complex, B
        vitamin.
        [WordNet 1.5]