From the ArcaMax Publishing, Vocabulary Newsletter:
http://www.arcamax.com/news/vocabulary/s-335018-612812
winsome \WIN-suhm\ (adjective) - 1 : Cheerful; merry; gay;
light-hearted. 2 : Causing joy or pleasure; agreeable; pleasant.
"Above all, it was winsome, devastatingly winsome. For a pretty face
to be winsome is normal enough and very winsome it can be, but it is a
tepid thing..." -- Mervyn Peake, 'The Gormenghast Novels'
Winsome is from Old English wynsum, from wynn, "joy" + -sum
(equivalent to Modern English -some), "characterized by."