Definition of "dreamer"

dreamer

/ˈdɹimɚ/

noun
plural dreamers
1. One who dreams.
2. Someone whose beliefs are far from realistic.
  Quotations
  You may say I'm a dreamer/ But I'm not the only one/ I hope someday you'll join us/ And the world will live as one.
  1971, John Lennon (lyrics and music), “Imagine”
3. Any anglerfish of the family Oneirodidae.
4. A swallow-wing puffbird (Chelidoptera tenebrosa)