S4

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

In arts, hobbies, and entertainment

• Yamaha grand piano model S4
• S4 standard, a standard of P4 gauge with reduced tolerance, a highly accurate 4 mm/1 ft railways modeling format
• Sonic the Hedgehog 4: Episode I, video game
• Super 4 (TV series), animated TV series that began in 2014

In science and technology

In biology and medicine

• Fourth heart sound, or S₄, an abnormal heart sound often indicative of congestive heart failure or cor pulmonale
• Sacral spinal nerve 4, a spinal nerve of the sacral segment
• Fourth sacrum of the vertebral column, in human anatomy

In computing

• Samsung Galaxy S4, a smartphone
  • Samsung Galaxy S4 Mini, a mini version of the Samsung Galaxy S4
• hibernation a sleeping state in which the contents of RAM are saved to a hard disk (Advanced Configuration and Power Interface code)
• S (programming language) version 4
• SG2 Shareable (Fire Control) Software Suite (S4)

In mathematics

• S4, a normal modal logic
• S4 algebra, a variety of modal algebras, also called Interior algebra
• Symmetric group S4 (S₄), an abstract mathematical group

In other sciences

• Tetrasulfur (S₄), an allotrope of sulfur
• British NVC community S4; see Swamps and tall-herb fens in the British National Vegetation Classification system
• S4: Keep away from living quarters, a safety phrase in chemistry

Other technologies

For uses in transportation, see section § In Transportation, below.

• Nikon Coolpix S4, a camera
• Sanyo DSC-4 and Sanyo Xacti DSC-4, cameras that have the Exif designation S4
• Source Four, an ERS theatre lighting fixture by Electronic Theatre Controls

In transportation

Air transport

• Letov Š-4, a 1923 Czechoslovak aircraft
• Hydra Technologies Ehécatl, S4, a Mexican unmanned aerial vehicle
• Seibel S-4, a 1951 helicopter
• SATA International (IATA airline designator)

Rail transport

• Alco S-4, a locomotive
• Prussian S 4, an 1894 steam locomotives class

Rail lines

• S4 (Berlin), a S-Bahn line
• S4 (Munich), a S-Bahn line in Munich
• 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

Road transport

• Audi S4, a car
• Lancia Delta S4, a 1984 Group B rally car
• County Route S4 (California), a road in San Diego, California

Other forms of transport

• Supermarine S.4, a 1925 British seaplane
• USS S-4 (SS-109), a 1919 US Navy submarine

Other uses

• S4 (military), a logistics officer within military units
• S-4 (Sector Four) an alleged facility in the Papoose Lake portion of Area 51 investigating alien spacecraft
• Form S-4, a form required by the Securities and Exchange Commission to declare mergers and acquisitions
• S04, or FC Schalke 04, a German professional sports club
• S postcode area, covering areas of northern Sheffield, England
• S4 (video gamer), a professional Dota 2 player.