alumnus vs pregraduate

alumnus

noun
  • A male graduate. 

  • A student of any gender. 

  • A male pupil or student. 

  • A graduate of any gender. 

pregraduate

noun
  • A person who is taking an academic course but has not yet graduated. 

adj
  • Of or pertaining to those studies that take place before a student completes a degree course. 

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