Ceinwen \ce(in)-wen\ as a girl's name is pronounced KAYN-wen, KINE-wen. It is of Welsh origin, and the meaning of Ceinwen is "beautiful and white, blessed". From "cain gwen". The plural "ceinion" means "beauties" or "gems", so the name is sometimes interpreted as "beautiful gems". Name of a fifth-century Welsh saint who gave her name to Keynsham near Bristol.
A baby name that sounds like Ceinwen is Zenina.