The name Gwendolen is a girl's name of Welsh origin meaning "white ring, circle". Gwendolen and is often added to lists like Names for December Babies and discussed in our forums with posts like "Favorite Full name for Nickname".
From the experts:
Gwendolen, an ancient Welsh favorite, retired decades ago in favor of the short form Gwen, but now, as in the case all across the naming board, the nickname has faded and the more distinguished original is up for reappraisal.
Gwendolen means "white circle," probably alluding to an ancient moon goddess, and appears in both Welsh and English legend, once as a fairy with whom King Arthur fell in love and another was the wife of the wizard Merlin.
Gwendolen is the name of principal characters in George Eliot's novel Daniel Deronda and in the Oscar Wilde play, The Importance of Being Earnest.
An alternate spelling is Gwendolyn, as in Gwendolyn Brooks, the first African-American woman to win a Pulitzer prize for poetry. Gwendolyn, always the more popular spelling in the U.S. and the full name of the character Winnie Cooper on The Wonder Years is now at Number 514, having reached as high as 112 in the 1950's.
Singer Gwen Stefani was actually christened Gwen.