From WordNet (r) 2.0 (August 2003) [wn]:
dreamer
n 1: someone who is dreaming
2: someone guided more by ideals than by practical
considerations [syn: idealist]
3: a person who escapes into a world of fantasy [syn:
escapist, wishful thinker]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Dreamer \Dream"er\ (dr[=e]m"[~e]r), n.
1. One who dreams.
[1913 Webster]
2. A visionary; one lost in wild imaginations or vain schemes
of some anticipated good; as, a political dreamer.
[1913 Webster]