S4

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

• S4 (gamer), Gustav Magnusson, Swedish Dota 2 player
• S4 (military), a logistics officer within military units

• County Route S4 (California), a road in San Diego, California

• S4 algebra, a variety of modal algebras, also called Interior algebra
• Tetrahedral symmetry, the symmetric group S₄
• S4, a normal modal logic

• S4: Keep away from living quarters, a safety phrase in chemistry
• Tetrasulfur (S₄), an allotrope of sulfur
• Andarine (S-4), a selective androgen receptor modulator and experimental drug

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

• S (programming language) version 4
• Hibernation a sleeping state in a computer
• SG2 Shareable (Fire Control) Software Suite (S4)
• Nikon Coolpix S4, a camera
• Samsung Galaxy S4, a smartphone
• Samsung Galaxy S4 Mini, a mini version of the Samsung Galaxy S4
• Samsung Galaxy Tab S4, an Android tablet

• S4 (Berlin), an S-Bahn line
• S4 (Munich), an S-Bahn line
• S4 (Nuremberg), an S-Bahn line
• S4 (Rhine-Main S-Bahn), an S-Bahn line
• S4 (Rhine-Ruhr S-Bahn), an S-Bahn line
• S4 (St. Gallen S-Bahn), an S-Bahn line in Switzerland
• S4 (RER Vaud), an S-Bahn line in Switzerland
• S4 (ZVV) line S4, a line of the S-Bahn Zürich in Switzerland
• Bremen S-Bahn line S4
• Hanover S-Bahn line S4
• Rhine-Neckar S-Bahn line S4
• Rostock S-Bahn line S4, a 2010-planned future line
• Stadtbahn Karlsruhe line S4
• Stuttgart S-Bahn line S4
• S4, a line of the Brussels Regional Express Network

• Alco S-4, a locomotive
• Audi S4, a car
• Lancia Delta S4, a 1984 Group B rally car
• Hydra Technologies Ehécatl, S4, a Mexican unmanned aerial vehicle
• Letov Š-4, a 1923 Czechoslovak aircraft
• Prussian S 4, an 1894 steam locomotives class
• Seibel S-4, a 1951 helicopter
• Supermarine S.4, a 1925 British seaplane
• USS S-4 (SS-109), a 1919 US Navy submarine

• S04, FC Schalke 04, a German professional sports club
• Shift4 Payments, a U.S. payment processor
• SATA International (IATA airline designator "S4"), Azores Airlines

• S4 (classification), a disability swimming classification
• Form S-4, a form required by the Securities and Exchange Commission to declare mergers and acquisitions
• S4 standard, a set of standards for model railways (P4 gauge)

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