'antimasonic' originates from the English formation combining the prefix 'anti-' (from Greek 'anti-' meaning 'against') and 'Masonic' (relating to 'Mason' / Freemasonry).

'antimasonic' was formed in English in the late 18th to early 19th century from 'anti-' + 'Masonic' (adjective relating to Freemasons); it became prominent during the 19th-century Anti-Masonic movement and the Anti-Masonic Party.

Initially and throughout its history it has meant 'against Freemasonry' or 'opposed to Freemasonry'; the core meaning has remained consistent, though historical usage has included organized political movements.