c. 1200, from Old English *heorcian "to hearken, listen," perhaps an intensive form from base of hieran (see hear). Compare talk/tale. Cognate with Old Frisian harkia "listen," Middle Dutch horken, Old High German horechon, German horchen. Used as a hunting cry to call attention. To hark back (1817) originally referred to hounds returning along a track when the scent has been lost, till they find it again (1814). Related: Harked; harking.