This is an irregular feature - both in frequency and oddness - dedicated to a word I came across that I have never previously used.
levirate - v. The practice of marrying the widow of one's brother after his death.
The purpose of a levirate marriage is typically to carry on the family line. The practice was mentioned in the Bible, but few groups permit the tradition today. The Roman Catholic Church specifically outlaws levirate marriage unless the original marriage was not consummated.
No Arkansas or Kentucky jokes, please.