Douglas Harper's Etymology Dictionary
nymphette
also nymphet, nymphete, "sexually attractive young girl," 1955, introduced by Vladimir Nabokov (1899-1977) in his novel "Lolita" to describe alluring (in the eyes of some men) girls age 9 to 14; from nymph + diminutive suffix. Used from 17c. in sense "a little nymph."
Wiktionary
nymphette
n. (alternative form of nymphet English)
Usage examples of "nymphette".
She makes Leila Carlea, the divine nymphette, look like a gods-forgotten lump.
In his dreams these charming nymphettes were climbing a ladder on their way to bed, and he was on duty beside the ladder watching them climb, catching glimpses of their slightly soiled knickers as they disappeared into the sky.