'antiaphthous' originates from New Latin/modern medical formation, specifically from Greek elements 'anti-' and 'aphtha', where 'anti-' meant 'against' and 'aphtha' meant 'ulcer; a small sore (especially in the mouth)'.

'antiaphthous' was coined in medical New Latin/English by combining Greek-derived elements: Greek 'anti-' + Greek 'aphtha' (ἀφθα). The element 'aphtha' led to the adjective 'aphthous' in English, and 'anti-' was prefixed to form 'antiaphthous' in 19th–20th century medical usage.

Initially it literally meant 'against aphtha (mouth ulcers)', and over time it has come to be used specifically for agents or treatments that prevent or heal aphthous ulcers.