Source : Webster's Revised Unabridged Dictionary (1913)

Heartache \Heart"ache`\, n. [Cf. AS. heortece.]
   Sorrow; anguish of mind; mental pang. --Shak.

Source : WordNet®

heartache
     n : intense sorrow caused by loss of a loved one (especially by
         death) [syn: {grief}, {heartbreak}, {brokenheartedness}]