'antifog' is a modern English formation combining the prefix 'anti-' (from Greek 'anti-' via Latin, meaning 'against') with the noun 'fog' (Old/Middle English).

'anti-' entered English as a productive prefix from Greek via Latin and French; 'fog' appears in Middle English as 'fogge' meaning mist or vapor, and the compound 'anti-' + 'fog' arose in the 20th century with the development of synthetic coatings and sprays.

The compound originally and consistently meant 'against fog' (i.e., a measure to prevent fogging); its usage has remained technical/compound, referring to agents, coatings, or treatments that prevent condensation and maintain visibility.