One of a pair.

一对中之一。

A couple.

一对。

A man's close-fitting garment for the upper half of the body worn in western Europe from the 15th to the 17th century.

(15至17世纪西欧盛行的一种)男用紧身上衣。

One of several words derived ultimately from the same source, but coming into a language through different channels, from different dialects, or at different periods, and differentiated in form or in meaning, e.g. frail and fragile.

同源异形字；同源异义字。

A pair of atomic, molecular, or nuclear quantum states that are usually close together in energy and arise from two possible orientations of spin.

量子偶对。

A pair of spectral frequencies of light arising from transitions to or from such quantum states.

(偶对量子的)双重光。

A pair of otherwise similar elementary particles (as a proton and a neutron) with different charges.

偶粒子；偶极子。