lieutenant junior grade vs subaltern

lieutenant junior grade

noun
  • A commissioned officer of the United States Navy whose rank is above an ensign's and below a lieutenant, or a corresponding rank in other navies. 

  • A commissioned officer in the United States Coast Guard, Public Health Service, or National Atmospheric and Oceanic Administration whose rank is above an ensign and below a lieutenant. 

subaltern

noun
  • A commissioned officer having a rank below that of captain; a lieutenant or second lieutenant. 

  • A subordinate. 

  • A subaltern proposition; a proposition implied by a universal proposition. 

  • A member of a group that is socially, politically and geographically outside of the hegemonic power structure of the colony and of the colonial homeland. 

adj
  • Asserting only a part of what is asserted in a related proposition. 

  • Of a lower rank or position; inferior or secondary; especially (military) ranking as a junior officer, below the rank of captain. 

How often have the words lieutenant junior grade and subaltern occurred in a corpus of books? (source: Google Ngram Viewer )