Having the qualities of a sylph, which is a slender, graceful, or delicate young woman or girl.
Sylphish is a word that makes people think of someone who is very graceful and pretty.
Examples:
She moved in a sylphish way, like a dancer.
The sylphish girl danced in the meadow.
Her sylphish movements were like a fairy's.
The sylphish ballerina twirled on her toes.
In the story, the princess was sylphish and could fly.
The sylphish girl glided through the room like a ghost.