Sentence:  A related marriage tradition is the <WSD>"sororate</WSD>" (Latin "soror" means “sister”), in which a man has the right to marry a (usually younger) sister of his deceased wife. In some societies, the <WSD>sororate</WSD> also applies to a man who has married a woman who is unable to bear children. 
Meaning of the word marked with <WSD> tags:  The custom of the marriage of a man to the sister of his wife, usually after the wife has died.