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”

An exciting or extraordinary scene, exhibition, performance etc.

“The horse race was a thrilling spectacle.”

An embarrassing or unedifying scene or situation.

“He made a spectacle out of himself.”

(usually in the plural) An optical instrument consisting of two lenses set in a light frame, and worn to assist sight, to obviate some defect in the organs of vision, or to shield the eyes from bright light.

A pair of lenses set in a frame worn on the nose and ears in order to correct deficiencies in eyesight or to ornament the face.