'age-denying' is a modern English compound formed from the noun 'age' and the verb 'deny' in its present participle form 'denying'. 'age' originates from Old French, specifically the word 'aage' (from Latin 'aetas'), where 'aetas' meant 'age'. 'deny' originates from Latin, specifically the word 'denegare', where 'de-' meant 'away' and 'negare' meant 'to deny'.

'age' entered English via Old French 'aage' from Latin 'aetas'; 'deny' entered via Old French from Latin 'denegare'. The compound 'age-denying' developed in modern English by combining 'age' + 'deny' + the present participle suffix '-ing', and appears in late 20th to 21st century usage especially in marketing and informal speech.

Initially, the phrase would have been interpreted literally as 'denying one's age'. Over time, especially in advertising and popular usage, it acquired an additional sense meaning 'counteracting visible aging' (as in 'age-denying cream').