Source : Webster's Revised Unabridged Dictionary (1913)

Goatee \Goat`ee"\, n.
   A part of a man's beard on the chin or lower lip which is
   allowed to grow, and trimmed so as to resemble the beard of a
   goat.

Source : WordNet®

goatee
     n : a small chin beard trimmed to a point; named for its
         resemblance to a goat's beard