Old English wynsum "agreeable, pleasant," from wynn "pleasure, delight," from Proto-Germanic *wunjo- (cognates: Old Saxon wunnia, Old High German wunja, German Wonne "joy, delight;" see win, v.) + -sum (see -some(1)). Apparently surviving only in northern English dialect for 400 years until revived 18c. by Hamilton, Burns, and other Scottish poets. Similar formation in Old Saxon wunsam, Old High German wunnisam. Related: Winsomely; winsomeness.