Source : Webster's Revised Unabridged Dictionary (1913)

Arrowhead \Ar"row*head`\, n.
   1. The head of an arrow.

   2. (Bot.) An aquatic plant of the genus {Sagittaria}, esp.
      {S. sagittifolia}, -- named from the shape of the leaves.

Source : WordNet®

arrowhead
     n : the pointed head or striking tip of an arrow