couplet vs pair

couplet

noun
  • A pair of two mutually exclusive choices in a dichotomous key. 

  • A pair of one-way streets which carry opposing directions of traffic through gridded urban areas. 

  • A pair of lines, typically with rhyming end words. 

pair

noun
  • One of the constituent items that make up a pair. 

  • A couple of working animals attached to work together, as by a yoke. 

  • A boat for two sweep rowers. 

  • A score of zero runs (a duck) in both innings of a two-innings match. 

  • Used with binary nouns (often in the plural to indicate multiple instances, since such nouns are plural only, except in some technical contexts) 

  • A double play, two outs recorded in one play. 

  • The exclusion of one member of a parliamentary party from a vote, if a member of the other party is absent for important personal reasons. 

  • Two similar or identical things taken together; often followed by of. 

  • Two members of opposite parties or opinion, as in a parliamentary body, who mutually agree not to vote on a given question, or on issues of a party nature during a specified time. 

  • In a mechanism, two elements, or bodies, which are so applied to each other as to mutually constrain relative motion; named in accordance with the motion it permits, as in turning pair, sliding pair, twisting pair. 

  • A doubleheader, two games played on the same day between the same teams 

  • A poker hand that contains two cards of identical rank, which cannot also count as a better hand. 

  • A pair of breasts 

  • A pair of testicles 

  • Two people in a relationship, partnership or friendship. 

verb
  • To engage (oneself) with another of opposite opinions not to vote on a particular question or class of questions. 

  • To group into one or more sets of two. 

  • To bring two (animals, notably dogs) together for mating. 

  • To suit; to fit, as a counterpart. 

  • To come together for mating. 

  • to link two electronic devices wirelessly together, especially through a protocol such as Bluetooth 

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