'BP' originates from English, specifically formed as an initialism from the initial letters of two-word terms such as 'blood pressure', 'British Petroleum', 'before present', and 'boiling point'.

'BP' developed as a written and spoken abbreviation in the 19th–20th centuries for medical notation ('blood pressure') and technical shorthand ('boiling point'); the time-scale abbreviation 'before present' arose with radiocarbon dating in the mid-20th century; the company name 'British Petroleum' was commonly shortened to 'BP' in branding and corporate usage (the company traces back to the Anglo-Persian Oil Company founded 1909 and later adopted the BP identity).

Initially used simply as a shorthand or notation for longer phrases, 'BP' has become a standalone label recognized across medicine, science, archaeology, and commercial branding with context-determined meanings.