Recorded in the spellings of Cassam, Casham, Cassom, Cossam, Cosham, Cossem, Cossom and Cossum, this is an English locational surname, one which is usually a slang form of the original. However spelt it probably originates from either the village of Corsham in Wiltshire, first recorded as Coseham in the year 760 a.d, or from the village of Cosham in Sussex, recorded in the famous Anglo-Saxon Chronicles in the year 1015 in the same spelling of Cosham. For a place to keep the same spelling over a (near) millenium is an almost unique occurence in itself. Both villages have exactly the same meaning of 'the homestead of the Cusa people', a personal or tribal name widely recorded in pre 7th century England. The surname is much later, and being locational is a 'from' surname. That is to say that the name was given to people after they left their original village, and moved elsewhere. Education over the centuries being at best problematical, and local dialects very thick, often lead to the development of 'sounds like' spellings, as with this name. Examples of recordings taken from early surviving church registers include: Georgius Cassam who married Agnete Eske at St Martins in the Field, Westminster, on October 14th 1554, Annes Cossem, christened at Ticehurst, Sussex, on November 19th 1570, Alice Cosham, christened at South Bersted, Sussex, on June 22nd 1576, Thomas Coshen, a witness at St Brides church, Fleet Street, City of London, on January 20th 1604, and Thomas Corsham of Ripe, Sussex, on May 24th 1756.