1. (noun)bacillus, B aerobic rod-shaped spore-producing bacterium; often occurring in chainlike formations; found primarily in soil
2. (noun)B-complex vitamin, B complex, vitamin B complex, vitamin B, B vitamin, B originally thought to be a singlevitamin but now separated into several B vitamins
3. (noun)boron, B, atomic number 5 a trivalent metalloid element; occurs both in a hard blackcrystal and in the form of a yellow or brownpowder