adjutant vs first lieutenant

adjutant

noun
  • A lower-ranking officer who assists a higher-ranking officer with administrative affairs. 

  • Any bird of the genus Leptoptilos, a branch of the stork family (Ciconiidae) native to India and Southeast Asia. 

  • An assistant. 

adj
  • Assistant; who helps a higher-ranking officer. 

first lieutenant

noun
  • 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. 

  • An equivalent rank in other military forces. 

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