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 S<sub>4</sub>
  • S4 (modal logic), a normal modal logic

Chemistry

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

Biology

  • Fourth heart sound, or S<sub>4</sub>, 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&nbsp;mm film 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

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)