sib - a person's brother or sisterfamily 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 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 |