ally vs couple

ally

verb
  • To join or unite (oneself or itself) against, with, etc., someone or something else. 

  • To unite or form a connection between (people or things), as between families by marriage, or between states by confederacy, league, or treaty. 

  • Chiefly followed by with: to enter into an alliance or unite for a common aim. 

  • Chiefly followed by to or with: to connect or form a relation to (someone or something) by similarity in features or nature. 

noun
  • Something regarded as connected with or related to another thing by similarity in features or nature. 

  • A person who co-operates with or helps another; an associate; a friend. 

  • A person who, or organization which, supports a demographic group subject to discrimination and/or misrepresentation but is not a member of the group; specifically (LGBT), a person who is not a member of the LGBT+ community but is supportive of it. 

  • A person, group, state, etc., which is associated or united by treaty with another for a common (especially military or political) purpose; a confederate. 

  • An organism which is related to another organism through common evolutionary origin; specifically, a species which is closely related to another species, usually within the same family. 

  • A person, group, concept, etc., which is associated with another as a helper; an auxiliary; a supporter. 

couple

verb
  • To join (two things) together, or (one thing) to (another). 

  • To cause (two animals) to copulate, to bring (two animals) together for mating. 

  • To join in sexual intercourse; to copulate. 

det
  • Two or a few, a small number of. 

noun
  • A small number. 

  • That which joins or links two things together; a bond or tie; a coupler. 

  • A couple-close. 

  • Two partners in a romantic or sexual relationship. 

  • One of the pairs of plates of two metals which compose a voltaic battery, called a voltaic couple or galvanic couple. 

  • Two of the same kind connected or considered together. 

  • A turning effect created by forces that sum to zero in magnitude but produce a non-zero external torque. 

adj
  • Two or (a) small number of. 

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