definition of
B

[1] #1 B n. [bacillus] aerobic rod-shaped spore-producing bacterium; often occurring in chainlike formations; found primarily in soil. wn

[2] #2 B n. [B-complex vitamin, B complex, vitamin B complex, vitamin B, B vitamin] originally thought to be a single vitamin but now separated into several B vitamins. wn

[3] #3 B n. [boron, atomic number 5] a trivalent metalloid element; occurs both in a hard black crystal and in the form of a yellow or brown powder. wn

[4] #4 B n. [Bel] a logarithmic unit of sound intensity equal to 10 decibels. wn

[5] #5 B n. [barn, b] (physics) a unit of nuclear cross section; the effective circular area that one particle presents to another as a target for an encounter. wn