Of a ring: such that all submodules of projective modules over the ring are also projective.
Of a title, honor or right: legally granted to somebody's descendant after that person's death.
Passed on as an inheritance, by last will or intestate.
Of a disease or trait: passed from a parent to offspring in the genes.
Of a person: holding a legally hereditary title or rank.
A hereditary ruler; a hereditary peer in the House of Lords.