due date vs trimester

due date

noun
  • The date of payment in financial arrangements. 

  • The date on which a pregnant woman is expected to give birth. 

  • The date by which a book (or other item) borrowed from a library must be returned. 

  • The date by which a task is supposed to be completed. 

trimester

noun
  • A period of three months or about three months; (financial): quarter. 

  • One of the terms of an academic year in those learning institutions that divide their teaching in three roughly equal terms, each about three months long. Compare semester. 

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