levirate

noun

1. the custom of marriage by a man with his brother’s widow, such marriage required in Biblical law if the deceased was childless. Deut. 25:5–10.

noun

1. the practice, required by Old Testament law, of marrying the widow of one’s brother

n.custom by which the male next-of-kin of a dead man was bound to marry his widow, 1725, from Latin levir “brother-in-law” (from PIE *daiwer- “husband’s brother”) + -ate (2).