Old English wynsum "agreeable, pleasant," from wynn "pleasure, delight," from Proto-Germanic *wunjo- (source also of Old Saxon wunnia, Old High German wunja, German Wonne "joy, delight"), from PIE root *wen- (1) "to desire, strive for" + -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.