An Etymological Dictionary of the German Language/Annotated/fein
fein, adjective, ‘fine, elegant, cunning,’ from Middle High German vîn, fîn, adjective, ‘fine, beautiful’; Old High German *fîn may be inferred from the adverb fînlîhho, which is first recorded in a gloss of the 10th century; compare Dutch fijn, English fine. Borrowed from a word common to Romance, Italian fino (French fin), with the primary meaning ‘perfect, genuine, pure,’ which is a late adjective form from Latin finire.