non-identical twin
noun [ C usually plural ] uk/ˌnɒn.aɪ.den.tɪ.kəl ˈtwɪn/ us/ˌnɑːn.aɪ.den.t̬ə.kəl ˈtwɪn/
非同卵双胞胎
one of a pair of twins (= two children born to the same mother on the same occasion) who do not look exactly the same because they developed from two separate eggs
Synonym: fraternal twin
Compare: dizygotic