From Middle English fin, fyn, from Old French fin (“fine, minute, exact”), probably from Latin finis (“a limit, end”), with an abstract sense of "fine" or "thin" also arising in many Romance languages (compare Spanish, Portuguese, and Italian fino).
From Old Irish fine, from Proto-Celtic *weniyā (“family”), from Proto-Indo-European *wenh₁- (“desire”); compare Old English wine (“friend”).
From Latin fīnis.
From Old Irish faigen (“sheath, scabbard”), from Latin vāgīna. Cognate with Irish faighin and Scottish Gaelic faighean.
From Old Frisian finda, which derives from Proto-Germanic *finþaną. Cognates include Föhr-Amrum North Frisian finj and West Frisian fine.
From Proto-Celtic *weniyā.
From Italian fine, and partly French fin.
From Old Frisian finda, from Proto-Germanic *finþaną, ultimately from Proto-Indo-European *pent-