Source : Webster's Revised Unabridged Dictionary (1913)

Uraeus \U*r[ae]"us\, n. [NL., fr. L. uraeus pertaining to a
   tail, Gr. ?, fr. ? tail.] (Egypt. Arch[ae]ol.)
   A serpent, or serpent's head and neck, represented on the
   front of the headdresses of divinities and sovereigns as an
   emblem of supreme power.