Source : Webster's Revised Unabridged Dictionary (1913)

Headspring \Head"spring`\, n.
   Fountain; source.

         The headspring of our belief.            --Stapleton.

Source : WordNet®

headspring
     n : the source of water from which a stream arises; "they
         tracked him back toward the head of the stream" [syn: {fountainhead},
          {head}]