1(of a title, office, or right) conferred by or based on inheritance:the Queen’s hereditary right to the throne
[attributive] (of a person) holding a position by inheritance:a hereditary peer
(of a characteristic or disease) determined by genetic factors and therefore able to be passed on from parents to their offspring or descendants:cystic fibrosis is our most common fatal hereditary diseaseeither hereditary or environmental factors
relating to inheritance:the main objection to the hereditary principle is that such peers are not elected
2 Mathematics (of a set) defined such that every element which has a given relation to a member of the set is also a member of the set.
late Middle English: from Latin hereditarius, from hereditas(see heredity)