sylph

n. being that inhabits the air (Mythology); slim and graceful woman or girl

For the ballet, see La Sylphide. For the hummingbird genus, see Aglaiocercus. Sylph is a mythological creature in the Western tradition. The term originates in Paracelsus, who describes sylphs as invisible beings of the air, his elementals of air. There is no substantial mythos associated with them.
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n. sylph, being that inhabits the air (Mythology)

(n.)
Fig.: A slender, graceful woman.
  

(n.)
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).
  

(n.)
An imaginary being inhabiting the air; a fairy.
  

[Folklore] A sylph is an immortal yet soulless (elemental) being that inhabits the air. They are mentioned by the medieval physician Paracelsus.