Meaning

noun a Louisianian descended from Acadian immigrants from Nova Scotia (`Cajun' comes from `Acadian')

originAn Anglicization of the Acadian French Cadien (itself an aphetic form of Acadien (“Acadian”)), reflecting the palatalization of /dj/ to /d͡ʒ/ in the Acadian dialect.

Etymology from Wiktionary, CC BY-SA 3.0