Levirate
Levirate (lev"i*rat) , adjective
[Latin levir a husband's brother, brother-in-law; akin to Greek dah`r: compare French lévirat leviration.]
Of, pertaining to, or in accordance with, a law of the ancient Israelites and other tribes and races, according to which a woman, whose husband died without issue, was married to the husband's brother.
The firstborn son of a leviratical marriage was reckoned and registered as the son of the deceased brother.
Also: Leviratical