Gollum's original name 'Sméagol' was not in fact the one he historically would have used: that name was Trahald. 'Trahald' comes from a Mannish dialect spoken in the region around the Gladden River, and means 'burrowing'. Tolkien created an anglicised version of the name, based on the Old English word smygel, which evolved into the better known name of Sméagol. The same old word for 'burrowing' lies behind smial, the Hobbits' traditional name for their hobbit-holes.
See also: Nahald.Ü