S33 may refer to:
Aviation Blériot-SPAD S.33, a French airliner Letov Š-33, a Czechoslovak bomber Madras Municipal Airport, in Jefferson County, Oregon, United States Short S.33, a variant of the Short S.27 British biplane of the 1910s Short S.33, a variant of the Short Empire British flying boat of the 1930s Sikorsky S-33 Messenger, an American sesquiplane Spectrum S-33 Independence, an American business jet
Naval vessels
, a torpedo boat of the Imperial German Navy
, a submarine of the United States Navy
Other uses S33 (Long Island bus) S33 (ZVV), a line of the Zürich S-Bahn County Route S33 (Bergen County, New Jersey) S33: Take precautionary measures against static discharges, a safety phrase Section 33 of the Canadian Charter of Rights and Freedoms Sotho language Sulfur-33, an isotope of sulfur S33, a postcode district in the Hope Valley, Derbyshire, England