Sidney Family History

habitational name from Sidney in Surrey and Lincolnshire, so named from Old English sid ‘wide’ + eg ‘island’, ‘dry island in a fen’, with the adjective retaining traces of the weak dative ending, originally used after a preposition and definite article. Two places in Cheshire called Sydney are from Old English sid + halh ‘nook’, ‘recess’ and may also be sources of the surname. possibly a habitational name from a place in Normandy called Saint-Denis, from the dedication of its church to St. Dionysius (see Dennis). There is, however, no evidence to support this derivation beyond occasional early modern English forms such as Seyndenys, which may equally well be the result of folk etymology.

Source: Dictionary of American Family Names ©2013, Oxford University Press