S4, S 4, Š-4, S.4 or S-4 may refer to:
People S4 (gamer), Gustav Magnusson, Swedish Dota 2 player S4 (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 Tetrahedral symmetry, the symmetric group S4 S4 (modal logic), a normal modal logic
Chemistry 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
Biology 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
Technology S (programming language) version 4 Hibernation (computing) a sleeping state in a computer SG2 Shareable (Fire Control) Software Suite (S4) Nikon S4, a 1958 35 mm film rangefinder camera 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
Transportation
Routes Austria S4, a Carinthia S-Bahn line S4, a Salzburg S-Bahn line that extends into Germany S4, a Tyrol S-Bahn line S4, an Upper Austria S-Bahn line S4, a Vienna S-Bahn line S4, a Vorarlberg S-Bahn line
Germany S4 (Berlin), a Berlin S-Bahn line S4 (Munich), a Munich S-Bahn line S4 (Nuremberg), a Nuremberg S-Bahn line S4 (Rhine-Main S-Bahn), a Rhine-Main S-Bahn line S4 (Rhine-Ruhr S-Bahn), a Rhine-Ruhr S-Bahn line S4, a Bremen S-Bahn line S4, a Hanover S-Bahn line S4, a Karlsruhe Stadtbahn, line S4, a Rhine-Neckar S-Bahn line S4, a planned Rostock S-Bahn line canceled in 2012 S4, a Stuttgart S-Bahn line
Switzerland S4 (St. Gallen S-Bahn), a St. Gallen S-Bahn line S4 (RER Vaud), an old number for RER Vaud S-Bahn line R4 S4 (ZVV), Zurich S-Bahn line
Other routes S4, a Brussels Regional Express Network line in Belgium Line S4 (Milan suburban railway service), Italy Line S4 (Nanjing Metro), China
Vehicles 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
Groups, companies, organizations S04, FC Schalke 04, a German professional sports club Shift4 Payments, a U.S. payment processor Azores Airlines, by IATA airline designator
Other 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)
See also
SSSS (disambiguation) 4S (disambiguation) S (disambiguation) 4 (disambiguation)