vitamin B complex

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A group of water-soluble vitamins including thiamine, riboflavin, niacin, pantothenic acid, biotin, pyridoxine, folic acid, inositol, and vitamin B₁₂ and occurring chiefly in yeast, liver, eggs, and some vegetables.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A group of water-soluble vitamins, once thought to be a single vitamin, occurring in yeast, liver, eggs etc.