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

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