1. 四连音：triplet 三连音 | quadruplet 四连音 | quintuplet 五连音

2. 四件一套的东西：quadruplet 四件一套的东西 | quadruplex 四路多工系统;四倍的;四重的;四路多工的 | quadruplication 放大四倍;反复四次

3. 四组：quadruple 四倍的 | quadruplet 四组 | quadruplex system 四路传输制

4. 四人骑的脚踏车：Push-Bike 脚踏车 (英国) | Quadruplet 四人骑的脚踏车 | Racer 比赛用的自行车

1. 四胞胎
Quadruplets are four children who are born to the same mother at the same time.

noun

1. a set of four similar things considered as a unit

Synonym: quartetquartettequadruple

2. one of four children born at the same time from the same pregnancy

Synonym: quad

3. the cardinal number that is the sum of three and one

Synonym: four4IVtetradquaternquaternionquaternaryquaternityquartetfoursomeLittle Joe