What is "sylphide"

Usage examples of "sylphide".

Conscientiously the child learned all the combinations -- how diligently she reversed her little feet in the pas de bourrée, how touchingly her roly-poly petit changement de pieds stood out against the changements of the practiced rats de ballet, how brightly, when Madame Lara practiced Little Swans with the children's class, shone Jenny's dust and time-dispelling gaze, which the austere Madame called her "Swan Lake look" -- and yet, for all the glamour that inevitably attaches to a ballerina, Jenny looked like a little pink pig trying to turn into a weightless sylphide.

Anatole, I was thinking, would no doubt give us of his best, possibly his Timbale de ris de veau Toulousaine or his Sylphides a la creme d'ecrevisses, but Spode would be there and Madeline would be there and Florence would be there and L.