"And we 'ave choirs of wood nymphs, 'oo serenade us as we eat."
-- Fleur Delacour (GF23)
Wood nymphs are small nature-loving creatures, who may be related to fairies or pixies.
Fleur told everyone at her table during dinner at the Yule Ball that the Christmas decorations at Beauxbatons included wood nymphs, who sing to the students as they eat (GF23).
Wood nymph is another name for dryads, which is a kind of tree nymph or tree spirit from Greek mythology. Some say these nature guardians live in trees, others say they are the trees, and transform into the forms of fair maidens. "Nymphs are generally regarded as divine spirits who animate nature, and are usually depicted as beautiful, young nubile maidens who love to dance and sing." (Wikipedia)
What are nature spirits? Are they beasts? Beings? Ghost? Who can say.
From the Web
"Wood Nymph" on the Harry Potter Wiki