Meaning of single-hearted

sin•gle-heart•ed

Pronunciation: (sing'gul-här'tid), [key]
— adj.
  1. sincere and undivided in feeling or spirit; dedicated; not reflecting mixed emotions: He was single-hearted in his patriotism.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.