Source : Webster's Revised Unabridged Dictionary (1913)

Sylph \Sylph\, n. [F. sylphe, m., fr. Gr. ? a kind of grub,
   beetle, or moth; -- so called by Paracelsus.]
   1. An imaginary being inhabiting the air; a fairy.

   2. Fig.: A slender, graceful woman.

   3. (Zo["o]l.) Any one of several species of very brilliant
      South American humming birds, having a very long and
      deeply-forked tail; as, the blue-tailed sylph ({Cynanthus
      cyanurus}).

Source : WordNet®

sylph
     n 1: a slender graceful young woman
     2: an elemental being believed to inhabit the air