This is a French locational surname. Recorded as Sein, Seine, de Seine, de Seins and Desseine, it has several possible origins. The first and most obvious is that it is locational and regional originating from residence in the department of Seine or by the River Seine, and this must surely apply to most nameholders. However the French Dictionary of Surnames gives two other alternatives. The first as Sein is claimed to be from the Basque country and to be a baptismal name or perhaps a nickname of endearment for a young child. As such it is equivalent to the French "enfant" or the English "child", whilst the second as Seine is also a nickname and a soubriquet for a "sinner", one who likes to fish in dangerous waters! Locational surnames are usually "from" names. That is to say surnames given to people who had left their original homes and had settled elsewhere. However where the preposition "de" is used, this implies nobility and ownership of the particular place. A coat of arms granted to the family of de Seins in Flanders has the blazon of a red field charged with a semee of lozenges conjoined in fesse, three, three, three and one