'veteran' originates from Latin, specifically the word 'veteranus', where 'vetus' meant 'old'.

'veteran' changed from Anglo-French/Old French 'veterain' and Latin 'veteranus' and eventually became the modern English word 'veteran' through Middle English.

Initially, it meant 'an old or long-experienced person, especially an old soldier'; over time it evolved into the current primary meaning of 'a person who has served in the armed forces' and more generally 'a person with long experience in a field.'