S is the nineteenth letter of the English alphabet.
S may also refer to:
South on a map, one of the 4 cardinal directionss, the SI symbol for secondShilling (British coin)S postcode area, a postcode area including Sheffield, EnglandA party label for the Swedish Social Democratic PartyStrike (baseball)S band, a band of radio which ranges from 2 to 4 GHzLanguage and linguistics
Long s (ſ), a form of the lower-case letter s formerly used where "s" occurred in the middle or at the beginning of a word-s, a suffix added to some English surnames, originally meaning "son of"s, the IPA symbol for a voiceless alveolar sibilant soundS, the subject of an intransitive verbMathematics and logic
Integral symbol (∫), used in mathematics to denote integrals and antiderivativesS combinator in combinatory logicSpheres(n), the aliquot sum of an integer nPhysics and chemistry
S, the chemical symbol for the element Sulfur on the periodic tableS, the symbol for entropyS, a non-SI unit used to designate molecule size named after the Svedberg sedimentation coefficientS, a label that denotes one of two chiral center configurations in the R/S systems, one of the Mandelstam variables, the square of the invariant massSiemens (unit), the SI derived unit of electric conductanceS-block of the periodic table, which includes alkali metals, alkaline earth metals, and hydrogen and heliumSpin (physics)Biology and medicine
Serine, a standard amino acid abbreviationATC code S Sensory organs, a section of the Anatomical Therapeutic Chemical Classification SystemS phase or synthesis phase, a period in the cell cycle during interphaseSamsung Galaxy S, the first flagship smartphone of the Samsung Galaxy S seriesS (programming language), an environment for statistical computing and graphics, the opening tag for the HTML element denoting information that is "no longer accurate or no longer relevant", usually rendered as strike-through textS. (Dorst novel), written by Doug Dorst based on story by J.J. AbramsS. (Updike novel), part of the Scarlet Letter trilogy by John UpdikeS (novel series), a 2005-2006 light novel seriesS, the pen name of Percy Bysshe Shelley"S.", the nickname for Solomon Shereshevsky (1886-1958), a Russian journalist, mnemonist, and synesthete notable for his unusual memory abilitiesS, the stage name of singer-songwriter and guitarist Jenn GhettoS (group), a short-lived South Korean music group active in 2003 and 2014S (EP), a 2001 EP by Japanese musical duo NaNaNumbering of Franz Liszt's works according to Humphrey Searle's catalogue 