'antitheft' originates from the combining of the prefix 'anti-' (from Greek 'anti-' meaning 'against') and the English noun 'theft' (from Old English 'þēof'/'þēofth' meaning 'thief' or the act of stealing').

'theft' changed from Old English 'þēofth' to Middle English forms such as 'thefte' and eventually to modern English 'theft'. The prefix 'anti-' entered English from Greek (via Latin and Old French influences) and was productive in modern English compounds like 'antitheft'.

Initially it literally meant 'against theft' and has retained that basic meaning; over time it became used specifically for devices or features that prevent theft ('antitheft device') and as an adjective describing such features.