'anti-knock' is a modern compound formed from the prefix 'anti-' (from Greek 'anti' meaning 'against') and English 'knock' (from Old English 'cnocian'/'cnocc' meaning 'to strike or knock').

'anti-' entered English as a productive prefix from Greek via Latin and later Modern English use; 'knock' evolved from Old English 'cnocian' through Middle English forms like 'knokken' to modern 'knock'. The compound 'anti-knock' arose in the 20th century with the development of internal-combustion engines and fuels.

Initially a literal combination meaning 'against knocking', it came to refer specifically to additives, fuels, or properties that prevent engine detonation (knocking).