'aginner' originates from American English, specifically a colloquial formation from 'agin' meaning 'against' and the suffix '-er' indicating a person.

'agin' transformed from the Middle English word 'agen' and eventually became the modern colloquial form 'agin' in American English.

Initially, it meant 'against,' but over time it evolved into its current meaning of 'a person who is against something.'