The Collaborative International Dictionary of English v.0.48:

Kwan yin \Kwan yin\, Kwan-yin \Kwan-yin\prop. n. (Buddhism)
   A female Bodhisattva; often called Goddess of Mercy and
   considered an aspect of the Bodisattva Avalokitesvara;
   identified with Japanese Kwannon.

   Syn: Kuan Yin.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Kwan-yin
    n 1: (Buddhism) a female Bodhisattva; often called goddess of
         mercy and considered an aspect of the Bodhisattva
         Avalokitesvara; identified with Japanese Kwannon [syn:
         Kwan-yin, Kuan Yin]