Sidney or Sydney is an English surname.
It is probably derived from an Anglo-Saxon locational name, [æt þǣre] sīdan īege, "[at the] wide island/watermeadow" (in the dative case).[1]
There is also a folk etymological derivation from the French place name Saint Denis.[2]
The name has also been used as a given name since the 19th century.
^Reaney, P.H. & Wilson, R.M. (1997) A dictionary of English surnames, revised edition Oxford University Press, New York, ISBN0-19-860092-5
^Hanks, P. & Hodges, F. (1988). A dictionary of surnames. Oxford University Press, New York, ISBN0-19-211592-8. "The name is usually derived from St. Denis but proof is lacking". Reaney, P.H. & Wilson, R.M. (1997)