Source : Webster's Revised Unabridged Dictionary (1913)

Monoceros \Mo*noc"e*ros\, n. [L., fr. Gr. ?; mo`nos alone,
   single + ke`ras horn.]
   1. A one-horned creature; a unicorn; a sea monster with one
      horn.

            Mighty monoceroses with immeasured tails. --Spenser.

   2. (Astron.) The Unicorn, a constellation situated to the
      east Orion.