first lieutenant vs senior

first lieutenant

noun
  • An equivalent rank in other military forces. 

  • The second lowest rank of a commissioned officer in the United States Army, Air Force, or Marine Corps, ranking above a second lieutenant and below a captain. The rank of first lieutenant is equivalent to the naval rank of lieutenant junior grade. 

senior

noun
  • Somebody who is higher in rank, dignity, or office. 

  • A final-year student at a high school or university. 

  • Someone seen as deserving respect or reverence because of their age. 

  • An old person. 

  • Someone older than someone else (with possessive). 

adj
  • Older; superior 

  • Higher in rank, dignity, or office. 

  • Of or pertaining to a student's final academic year at a high school (twelfth grade) or university. 

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