Gee, Merriam-Webster has it listed as a valid English word, derived from the German. I'll have to make use of it the next time I play Scrabble.

Wiktionary also has a listing for it as an english word borrowed from the German.

Definition is as above, a teenage or late adolescent girl. I suppose it's at least a bit sexist and not appropriate in our enlightened times. I won't be adding it to my vocabulary.

-Joe-