0 abbreviation for Before Christ: used in the Christian calendar when referring to a year before Jesus Christ was born: --
The Battle of Actium took place in 31 BC.
1 written abbreviation for because: used, for example, on social media or in text messages: --
2 abbreviation for Before Christ, used to show that a year or century comes before the year in which Jesus Christ is thought to have been born: --
Caesar was assassinated in 44 B.C.