first lieutenant vs officer

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. 

officer

noun
  • One who has a position of authority in a hierarchical organization, especially in military, police or government organizations. 

  • A respectful term of address for an officer, especially a police officer. 

  • One who holds a public office. 

  • An agent or servant imparted with the ability, to some degree, to act on initiative. 

  • A commissioned officer. 

verb
  • To supply with officers. 

  • To command as or like an officer. 

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