peer group
noun [ C usually singular, + sing/pl verb ] uk/ˈpɪə ˌɡruːp/ us/ˈpɪr ˌɡruːp/
同龄群体;同辈群体
the people who are approximately the same age as you and come from a similar social group
These children scored significantly lower on intelligence tests than others in their peer group. 这些孩子在智力测验中所得的分数远远低于同龄群体中的其他孩子。