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

People

* S4 (Dota player), Gustav Magnusson, Swedish ''Dota 2'' player *

S4 (military) A military staff or general staff (also referred to as army staff, navy staff, or air staff within the individual services) is a group of officers, enlisted and civilian staff who serve the commander of a division or other large military ...

, a logistics officer within military units

Places

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

Science and mathematics

Mathematics

* S4 algebra, a variety of modal algebras, also called Interior algebra *

Symmetric group S4 Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definit ...

(S₄), an abstract mathematical group * S4, a

normal modal logic In logic, a normal modal logic is a set ''L'' of modal formulas such that ''L'' contains: * All propositional tautologies; * All instances of the Kripke schema: \Box(A\to B)\to(\Box A\to\Box B) and it is closed under: * Detachment rule ('' modus ...

Chemistry

* S4: Keep away from living quarters, a safety phrase in chemistry * Tetrasulfur (S₄), an allotrope of sulfur

Biology

* Fourth heart sound, or S₄, an abnormal heart sound often indicative of congestive heart failure or cor pulmonale * Fourth

sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part ...

of the vertebral column in human anatomy *

Sacral spinal nerve 4 The sacral spinal nerve 4 (S4) is a spinal nerve of the sacral segment.American Medical Association

, a spinal nerve of the sacral segment

Technology
*
S (programming language) S is a statistical programming language developed primarily by John Chambers and (in earlier versions) Rick Becker and Allan Wilks of Bell Laboratories. The aim of the language, as expressed by John Chambers, is "to turn ideas into software, qui ...
version 4 * Hibernation a sleeping state in a computer *
SG2 Shareable (Fire Control) Software Suite (S4) The NATO Army Armaments Group (NAAG) Integrated Capability Group Indirect Fires (ICGIF), formerly Land Group 4, and their Sub Group 2 (SG2) on Surface to Surface Ballistics has created a widely used set of shareable fire control software using th ...
* Nikon Coolpix S4, a camera *
Samsung Galaxy S4 The Samsung Galaxy S4 is an Android smartphone produced by Samsung Electronics as the fourth smartphone of the Samsung Galaxy S series and was first shown publicly on March 14, 2013, at Samsung Mobile Unpacked in New York City. It is the succes ...
, a smartphone *
Samsung Galaxy S4 Mini The Samsung Galaxy S4 Mini (stylized as Samsung GALAXY S4 mini) is an Android smartphone developed by the Korean manufacturer Samsung Electronics. Announced on May 31, 2013 and released in July 2013, the S4 Mini is a mid-range model of its flagsh ...
, a mini version of the Samsung Galaxy S4 * Samsung Galaxy Tab S4, an Android tablet

Transportation

Routes
* S4 (Berlin), an S-Bahn line * S4 (Munich), an S-Bahn line * S4 (Nuremberg), an S-Bahn line *
S4 (Rhine-Main S-Bahn) The S4 service of the S-Bahn Rhein-Main system bearing the KBS (German scheduled railway route) number 645.4 Routes Kronberg Railway Homburg Railway City tunnel The city tunnel is an underground, pure S-Bahn route used by almost a ...
, an S-Bahn line * S4 (Rhine-Ruhr S-Bahn), an S-Bahn line *
S4 (St. Gallen S-Bahn) The S4 is a railway service of the St. Gallen S-Bahn that provides hourly service over a circular route (german: Ringzug) that includes , , and , in the canton of St. Gallen. Südostbahn, a private company primarily owned by the federal governme ...
, an S-Bahn line in Switzerland * S4 (RER Vaud), an S-Bahn line in Switzerland *
S4 (ZVV) The Sihltal railway line (german: Sihltalbahn) is a railway line in the Swiss canton of Zürich, which connects the city of Zürich with the communities of the Sihl Valley. Passenger service on the line now forms part of the Zürich S-Bahn, br ...
line S4, a line of the S-Bahn Zürich in Switzerland *
Bremen S-Bahn The Bremen S-Bahn (german: Regio-S-Bahn Bremen/Niedersachsen) is an S-Bahn network in Germany, covering the Bremen/Oldenburg Metropolitan Region, from Bremerhaven in the north to Twistringen in the south and Bad Zwischenahn and Oldenburg in t ...
line S4 *
Hanover S-Bahn The Hanover S-Bahn (in German: ''S-Bahn Hannover'') is an S-Bahn network operated by DB Regio and Transdev Hannover in the area of Hanover in the German state capital of Lower Saxony. It went operational shortly before Expo 2000 and is focused on ...
line S4 * Rhine-Neckar S-Bahn line S4 *
Rostock S-Bahn The Rostock S-Bahn (german: S-Bahn Rostock) is a S-Bahn (suburban railway) network in Rostock in the German state of Mecklenburg-Vorpommern. It consists of three lines with a total length of about 90 km. Line S1 runs from Rostock Hauptbahnhof ...
line S4, a 2010-planned future line *
Stadtbahn Karlsruhe The Karlsruhe Stadtbahn is a German tram-train system combining tram lines in the city of Karlsruhe with railway lines in the surrounding countryside, serving the entire region of the middle upper Rhine valley and creating connections to neighb ...
line S4 *
Stuttgart S-Bahn The Stuttgart S-Bahn is a suburban railway system (S-Bahn) serving the Stuttgart Region, an urban agglomeration of around 2.7 million people, consisting of the city of Stuttgart and the adjacent districts of Esslingen, Böblingen, Ludwi ...
line S4 * S4, a line of the
Brussels Regional Express Network The Brussels S-train, also known as the Brussels Regional Express Network (french: Réseau Express Régional Bruxellois or RER); ( nl, Gewestelijk ExpresNet or GEN) is a suburban rail system in the Brussels Capital Region. It will offer fast conne ...

Vehicles
* Alco S-4, a locomotive *
Audi S4 The Audi S4 is the high performance variant of Audi's compact executive car A4. The original Audi S4, built from 1991 until 1994, was a performance-oriented version of Audi's 100 saloon/sedan. All subsequent S4s since 1997 have been based on th ...
, a car *
Lancia Delta S4 The Lancia Delta S4 is a Group B rally car manufactured by the Italian car company Lancia. The Delta S4 competed in the World Rally Championship in 1985 and 1986, until Group B class was disbanded and the cars were eventually banned from competi ...
, a 1984 Group B rally car *
Hydra Technologies Ehécatl The S4 Ehécatl is an unmanned aerial vehicle developed and manufactured by Hydra Technologies of Mexico which, except for its infrared thermal sensor system, is the first of its type to be completely designed and manufactured in Mexico. It is nam ...
, S4, a Mexican unmanned aerial vehicle * Letov Š-4, a 1923 Czechoslovak aircraft *
Prussian S 4 The Prussian S 4's were German superheated express steam locomotives with the Prussian state railways, later grouped as DRG Class 13.5 in the Deutsche Reichsbahn. They were an evolutionary development of the Prussian S 3. The first locomotive wa ...
, an 1894 steam locomotives class * Seibel S-4, a 1951 helicopter * Supermarine S.4, a 1925 British seaplane *
USS S-4 (SS-109) USS ''S-4'' (SS-109) was an S-class submarine of the United States Navy. In 1927, she was sunk by being accidentally rammed by a United States Coast Guard destroyer with the loss of all hands but was raised and restored to service until stric ...
, a 1919 US Navy submarine

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

Other
*
S4 (classification) S4, SB3, SM4 are disability swimming classifications used for categorising swimmers based on their level of disability. Swimmers in this class have coordination problems affecting all four of their limbs, or have movement in their arms but no tr ...
, 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)

See also
* * SSSS (disambiguation) * 4S (disambiguation) * S (disambiguation) * 4 (disambiguation) {{Letter-NumberCombDisambig