'anti-masker' is a modern English compound formed from the prefix 'anti-' (meaning 'against'), the noun 'mask' (meaning a face covering), and the agentive suffix '-er' (denoting a person). The coinage became common in English during the 2020s in the context of debates over public-health mask policies.

'mask' comes from Middle French 'masque' and Italian 'maschera', originally from Medieval Latin 'masca' (which could mean 'mask' or 'witch'); 'anti-' derives from Greek 'anti-' via Latin and Old French; the English agentive suffix '-er' is from Old English/Germanic agent-forming elements. These parts combined in modern English to form 'anti-masker'.

Individually the parts retained their meanings ('anti-' = against; 'mask' = face covering; '-er' = person who does), but the compound 'anti-masker' specifically came to mean a person opposed to mask-wearing in public-health contexts.