Si
SI is the International System of Units.
SI, Si, or si may also refer to:
Arts, entertainment, and media
Literature
- Si (novel), a 2014 novel by Bob Ong
- Sí (Peruvian magazine), a magazine notable for its anti-corruption reporting
- Skeptical Inquirer, an American magazine covering topics on science and skepticism
- Sports Illustrated, an American sports magazine
- Soccer International, an Australian monthly magazine
Music
- Sí (Julieta Venegas album), released in 2003
- Sì (Andrea Bocelli album), released in 2018
- "Sí" (Martin Jensen song), a 2015 song
- Si (musical note), the seventh note in the traditional fixed do solfège
- Sì (operetta), an operetta by the Italian composer Pietro Mascagni
- "Sì" (Gigliola Cinquetti song), the Italian entry to the Eurovision Song Contest 1974
- Si (Zaz song), 2013
- Sí, a 2013 Spanish album by Malú
- "Sì", a 1985 song released by Italian actress Carmen Russo
Other uses in arts, entertainment, and media
- Si (film), original title of the 2010 South Korean film Poetry
Enterprises and organisations
Computing
- Swiss Informatics Society, a Swiss organization of computer science educators, researchers, and professionals
- The SI, a former name of the American defense contractor Vencore
Education
- St. Ignatius College Preparatory, a Jesuit high school in San Francisco, California, US
- Silay Institute, a private college in the Philippines
Government
- Si, a South Korean administrative unit
- Survey of India, an Indian government agency responsible for managing geographical information
- Swedish Institute (Svenska institutet), a Swedish government agency which promotes Sweden abroad
Politics
- Sarekat Islam, a socio-political organization in Indonesia under Dutch colonial rule
- Catalan Solidarity for Independence, a Catalan political party
- Situationist International, an organization of social revolutionaries
- Socialist International, a worldwide organization of political parties
- Solidarity and Equality, an Argentine political party (Spanish: Solidaridad e Igualdad)
Transportation
- Blue Islands (IATA airline code, SI)
- Skynet Airlines (IATA airline code SI, ceased operating 2004)
- Spokane International Railroad (reporting mark SI), a former railway in Washington, US
Other enterprises and organizations
- Samahang Ilokano, a fraternity/sorority based in the Philippines
- SÍ Sørvágur, a Faroese sports association
- Society of Indexers, a professional society based in the UK
- Sports Interactive, a British computer games development company
People with the name
- Si (surname), a Chinese surname
- Si (given name)
- Princess Si of Anding,first daughter of Wu zetain
Places
- Mount Si, a mountain in the U.S. state of Washington
- Si (ancient Seeia/Seia), northern Hauran (ancient Auranitis), Syria; archaeological site with Nabataean temples, necropolis
- Province of Siena (postal code and vehicle registration plate code)
- Si County, Anhui, China
- Si River, in China
- Slovenia's ISO 3166-2 code
- Sukabumi railway station (SI), a railway station in Sukabumi, Indonesia
Science and technology
Biology and healthcare
- Smithsonian Institution (SI is its international code)
- Sacroiliac, an anatomical abbreviation for the sacroiliac (joint)
- Self-injury, intentional, direct injuring
- Suicidal ideation, thoughts of suicide
- Shock index, a measurement used to determine if a person is suffering shock
Chemistry
- si, a chemical descriptor; See prochirality
- Silicon, symbol Si, a chemical element
- Disulfur diiodide, empirical formula SI
Computing and Internet
- .si, the Internet country code top-level domain for Slovenia
- Shift In, an ASCII control character
- SI register, or source index, in X86 computer architecture
- Swarm intelligence, an artificial intelligence technique
- Synthetic intelligence, an alternate term for or a form of artificial intelligence
Motor vehicles
- Honda Civic Si, an automobile
- Spark-ignition engine, a type of internal combustion engine
Other uses in science and technology
- Signal integrity, electronic circuit tools and techniques that ensure electrical signals are of sufficient quality
- Sine integral, Si(x)
- Spectral interferometry, attosecond physics technique
- Systems integrator, in engineering
Titles and ranks
- Si, a Maghrebi Arabic variant of Sidi, a title of respect
- Si, a variant of the Thai honorific Sri
- Station inspector, a rank in the Singapore Police Force
- Sub-inspector, a rank in Indian Police forces
Other uses
- Statutory instrument (UK), abbreviated SI, the principal form in which delegated legislation is made in Great Britain
- Sì (dessert), a Chinese dessert
- Template:Lang, Template:Lang, or Template:Lang, Celtic mythological beings
- si, the Sinhala language ISO 639 alpha-2 code
- Supplemental instruction, an academic support program often used in higher education