pair

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

“I couldn't decide which of the pair of designer shirts I preferred, so I bought the pair.”

Two people in a relationship, partnership or friendship.

“Spouses should make a great pair.”

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

“a pair of scissors; two pairs of spectacles; several pairs of jeans”

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

“A pair is harder to drive than two mounts with separate riders.”

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

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

A double play, two outs recorded in one play.

“They turned a pair to end the fifth.”

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

“The Pirates took a pair from the Phillies.”

A boat for two sweep rowers.

A pair of breasts

“She's got a gorgeous pair.”

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 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.

“There were two pairs on the final vote.”

A number of things resembling one another, or belonging together; a set.

(kinematics) 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.

To group into one or more sets of two.

“The wedding guests were paired boy/girl and groom's party/bride's party.”

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

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

To suit; to fit, as a counterpart.

To impair, to make worse.

To become worse, to deteriorate.