S4

S4, S 4, Š-4, S.4 or S-4 may refer to:

Beginning with S4

• S4 standard, a standard of P4 gauge with reduced tolerance, a highly accurate 4 mm/1 ft railways modeling format
• S4, a sustainability trends in fashion newsletter created by model Summer Rayne Oakes
• S4, a normal modal logic
• S4 algebra, a variety of modal algebras, also called Interior algebra
• S4 (Berlin), a S-Bahn line
• S4: Keep away from living quarters, a safety phrase in chemistry
• S4 (military), a logistics officer within military units
• S4 (Munich), a S-Bahn line in Munich
• S postcode area, covering areas of northern Sheffield
• S-4 (Sector Four) an alleged facility in the Papoose Lake portion of Area 51 investigating alien spacecraft

Containing S4

• Alco S-4, a locomotive
• Audi S4, a car
• British NVC community S4, a swamps and tall-herb fens in the British National Vegetation Classification system
• County Route S4 (California), a road in San Diego, California
• Form S-4, a form required by the Securities and Exchange Commission to declare mergers and acquisitions
• Hydra Technologies Ehécatl, S4, a Mexican unmanned aerial vehicle
• Lancia Delta S4, a 1984 Group B rally car
• Letov Š-4, a 1923 Czechoslovak aircraft
• Nikon Coolpix S4, a camera
• Prussian S 4, an 1894 steam locomotives class
• Samsung Galaxy S4, a smartphone
• Samsung Galaxy S4 Mini, a mini version of the Samsung Galaxy S4
• Sanyo DSC-4 and Sanyo Xacti DSC-4, cameras that have the Exif designation S4
• Seibel S-4, a 1951 helicopter
• Supermarine S.4, a 1925 British seaplane
• USS S-4 (SS-109), a 1919 US Navy submarine

S₄

• Fourth heart sound, an abnormal heart sound often indicative of congestive heart failure or cor pulmonale
• Tetrasulfur, an allotrope of sulfur
• Symmetric group S4, an abstract mathematical group

S04

• S04, a code name for FC Schalke 04

As a code

• hibernation a sleeping state in which the contents of RAM are saved to a hard disk (Advanced Configuration and Power Interface code)
• SATA International (IATA airline designator)
• S (programming language) version 4
• Sacral spinal nerve 4, a spinal nerve of the sacral segment
• Fourth sacrum of the vertebral column, in human anatomy
• S-4 (Sector Four), an alleged military base next to Area 51, said to contain nine UFOs
• Yamaha grand piano model S4

As an abbreviation

• Sonic 4 (disambiguation)
• Source Four, an ERS theatre lighting fixture by Electronic Theatre Controls
• Super 4 (disambiguation)

As an acronym

• SG2 Shareable (Fire Control) Software Suite (S4)

As a train line

• Bremen S-Bahn line S4
• Hanover S-Bahn line S4
• RheinNeckar S-Bahn line S4
• Rhein-Ruhr S-Bahn line S4
• Rhine-Main S-Bahn line S4
• Rostock S-Bahn line S4, a 2010-planned future line
• Stuttgart S-Bahn line S4
• S4 (ZVV) line S4, a line of the S-Bahn Zürich in Switzerland
• Stadtbahn Karlsruhe line S4