family unit, family - primary social group; parents and children; "he wanted to have a good job before starting a family"

half blood - on of siblings who have only one parent in common

relative, relation - a person related by blood or marriage; "police are searching for relatives of the deceased"; "he has distant relations back in New Jersey"

quad, quadruplet - one of four children born at the same time from the same pregnancy

quin, quint, quintuplet - one of five children born at the same time from the same pregnancy

triplet - one of three offspring born at the same time from the same pregnancy

twin - either of two offspring born at the same time from the same pregnancy