- 二重唱 èrchóngchàng dueta vocal duet where two singers or two groups of singers sing different parts together
- 二重奏 èrchóngzòu duetinstrumental duet; a musical performance where two instruments play different parts together
- 二重性 èrchóngxìng dualityThe state of having two opposite or contradictory qualities or natures; dual character.
- 二重根 èrchónggēn double roota double root of an equation
- 二重母音 èrchóngmǔyīn diphthonga complex vowel sound formed by two vowels in a single syllable; complex nucleus
- 二重下标 èrchóngxiàbiāo double subscriptdouble subscript; doubly indexed
- 二重国籍 èrchóngguójí dual nationalityThe status of a person who is concurrently a citizen of two different countries, such as by birth or through marriage