Source : Webster's Revised Unabridged Dictionary (1913)

Narcissus \Nar*cis"sus\, n.; pl. {Narcissuses}. [L. narcissus,
   and (personified) Narcissus, Gr. na`rkissos, Na`rkissos, fr.
   na`rkh torpor, in allusion to the narcotic properties of the
   flower. Cf. {Narcotic}.]
   1. (Bot.) A genus of endogenous bulbous plants with handsome
      flowers, having a cup-shaped crown within the six-lobed
      perianth, and comprising the daffodils and jonquils of
      several kinds.

   2. (Classical Myth.) A beautiful youth fabled to have been
      enamored of his own image as seen in a fountain, and to
      have been changed into the flower called Narcissus.

Source : WordNet®

narcissus
     n 1: bulbous plant having erect linear leaves and showy yellow or
          white flowers either solitary or in clusters
     2: (Greek mythology) a beautiful young man who fell in love
        with his own reflection
     [also: {narcissi} (pl)]