The Collaborative International Dictionary of English v.0.48:
Annwfn \Annwfn\ n. 1. 1 (Welsh mythology) the other world; land of fairies. Syn: Annwn. [WordNet 1.5]WordNet (r) 3.0 (2006):
Annwfn n 1: (Welsh mythology) the other world; land of fairies [syn: Annwfn, Annwn]