This unusual and interesting name is of Medieval English origins, and is believed to be one of the metonymic forms of name "Moll", itself a pet form of "Mary". "Mary" was not known in England until introduced by the Crusaders, between the 11th and 13th Century, but thereafter because the most popular female name of the intervening Centuries. Mourson, Mosson, Mossum, Mosen, Mossam, Mosum etc. all have the same meaning of "the son of Mo(ll)", and these variants are unusual in being amongst the few survivors of names derived from the first bearers mother, rather than father. The examples of the name recording include Charles Mossom, a christening witness of his daughter Martha, at the Church of St. Martins in the Field, Trafalgar Square, London on August 31st 1681. The first recorded spelling of the family name is shown to be that of Nicholas Mosum, which was dated September 6th 1598, a witness at the Church of St. Anne's, Blackfriars, London, during the reign of Queen Elizabeth 1, "Good Queen Bess", 1558 - 1603. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.