sibship
/ˈsɪbʃɪp/noun
1- chiefly Zoology a group of offspring having the same two parents【主动】(同父母的)兄弟姊妹, 同胞。
1.1
- mass noun Anthropology the state of belonging to a sib or the same sib【人类学】同族关系, 血亲关系。