UK:*UK and possibly other pronunciationsUK and possibly other pronunciations/əˈɡɪn/US:USA pronunciation: respellingUSA pronunciation: respelling(ə gin)

WordReference Random House Unabridged Dictionary of American English © 2020
a•gin  (ə gin),USA pronunciation prep. [Dial.]
  1. Dialect Terms, Slang Termsagainst;
    opposed to.
  • see again 1815–25

Collins Concise English Dictionary © HarperCollins Publishers::
agin /əˈɡɪn/ prep
  1. an informal, facetious, or dialect word for against
Etymology: 19th Century: from obsolete again against
'agin' also found in these entries (note: many are not synonyms or translations):
Report an inappropriate ad.