'anti-mask' is a modern English compound formed from the prefix 'anti-' (from Greek 'anti', meaning 'against') plus 'mask' (from Italian/French 'maschera'/'masque', meaning a covering).

'mask' comes via Italian 'maschera' and French 'masque' from Late Latin 'masca' (meaning 'witch' or 'specter'); 'mask' developed to mean a face covering. The prefix 'anti-' comes from Greek 'anti-' meaning 'against'; the compound 'anti-mask' arose in contemporary English (notably during the COVID-19 pandemic) to label opposition to mask-wearing.

Originally, elements like 'masca' referred to supernatural beings ('witch'/'specter'), but 'mask' evolved to mean a physical face covering; 'anti-' has long meant 'against', and combined with 'mask' it now specifically denotes opposition to face coverings (esp. in public-health contexts).