schoolgirl vs young lady

schoolgirl

verb
  • To restrain in a schoolgirl pin. 

noun
  • A girl attending school. 

young lady

noun
  • Used other than figuratively or idiomatically: see young, lady. 

  • A term of endearment or admonishment by adults for a young girl. 

How often have the words schoolgirl and young lady occurred in a corpus of books? (source: Google Ngram Viewer )