SL

SL may refer to:

• Serjeant-at-law, an obsolete legal position in the United Kingdom
• Sensei's Library, an internet website and wiki dedicated to the ancient game of Go
• Sensu lato, a term used in taxonomy to mean "in the wider sense" of a definition
• Standard length, a commonly used measurement for fish: the length from tip of the snout to the posterior end of the last vertebra

Geography

• Saint Lucia, a Caribbean island
• The SL postcode area of the United Kingdom
• Sri Lanka, in South Asia
• Sierra Leone, in West Africa

Computing

• SL (complexity), a class of computational complexity
• .sl, the country code top-level domain for Sierra Leone
• Second Life, a multi-user 3D virtual world
• Scientific Linux, a Linux distribution
• Service Loading, a variant of WAP push method
• Subjective logic, a type of probabilistic logic
• sl, a humorous command in Linux and other Unix systems that draws a steam locomotive in ASCII art, intended to be invoked as a typo of ls

Mathematics

• Sine lemniscate function
• Special linear group, a term used in mathematics, denoted SL_n
• Sturm-Liouville theory, a theory of a particular class of differential equations

Languages

• Sign language
• Slovene language, in ISO 639-1 code
• sl (digraph), a Latin-script digraph

Transport

• Mercedes-Benz SL-Class, an automobile
• Rio Sul Serviços Aéreos Regionais, IATA code SL, a Brazilian airline
• Thai Lion Air, IATA airline code
• Salt Lake City Southern Railroad's reporting mark
• Steam locomotive
• Stor-Oslo Lokaltrafikk, a public transport operator in Akershus, Norway
• Storstockholms Lokaltrafik, a public transport operator in Stockholm, Sweden

Organizations

• Sendero Luminoso, the "Shining Path" Maoist guerrilla movement
• SL Corporation, a Korean auto parts company
• Stronnictwo Ludowe, a defunct Polish party

Other

• Sine loco, a term used in bibliographies to indicate that the place of publication of a document is unknown
• Sociedad de Responsabilidad Limitada, the Spanish variant of a limited liability company (LLC)
• Sonoluminescence, the emission of short bursts of light from imploding bubbles in a liquid when excited by sound
• Sophrolaelia, an orchid genus
• Sharia law, the Muslim legal system