Sidney
SID-nee
A place-based name that came into English as a surname and later became a given name.
Meaning
Sidney began as a surname derived from a place-name, later adopted as a given name. In the provided sources, it is explicitly linked to the spelling variant "Sydney," but no fuller etymology is given there. In common onomastic use, it is treated as a transferred surname/place-name rather than a name with a transparent literal meaning.
Origin
EnglishOld Frenchvaries by culture
Fun fact
The excerpts note the variant spelling "See SYDNEY," showing that Sidney and Sydney have long been treated as closely related forms.
Confidence: mixed. Sources: Praenomina; or, the etymology of the principal Christian names of Great Britain and Ireland.