Moiety may refer to: 1  Moiety (chemistry) , a part or functional group of a molecule. 2  Moiety (kinship) , either of two groups into which a society is divided. 3  An Australian Aboriginal kinship group.oiety may refer to: 1  Moiety (chemistry) , a part or functional group of a molecule. 2  Moiety (kinship) , either of two groups into which a society is divided. 3  An Australian Aboriginal kinship group.