Definition of Year Of Mourning
The Roman "annus luctus” (q.v.) The reason for the widow’s year of mourning has been stated as follows: "But if a man dies, and his widow soon after marries again, and a child is born within such a time as by the course of nature it might have been the child of either husband, in this case he is said to be more than ordinarily legitimate; for he may, when he arrives at years of discretion, choose which of the fathers he pleases. To prevent this, the civil law ordained that no widow should marry for one year, and the same constitution was probably transmitted to our ancestors from the Romans, during their stay in Britain, for we find it established under the Saxon and Danish governments.” 1 Bl.Comm. 456.
That's the definition of Year Of Mourning in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.