dyad
noun [ C ] uk/ˈdaɪ.æd/ us/ˈdaɪ.æd/
formal二元体，二分体
something that consists of two parts
social science specialized（社会关系）二人组合（如夫妻）
a group of two people, which is the smallest possible social group
the marital dyad 夫妻二人
mother-infant dyads 母婴二人