SL may refer to:

  • 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
  • Serjeant-at-law, an obsolete legal position in the United Kingdom
  • Signed Log, a term found often in Geocaching log entries
  • Sine loco, a term used in bibliographies to indicate that the place of publication of a document is unknown
  • Sonoluminescence, the emission of short bursts of light from imploding bubbles in a liquid when excited by sound
  • Sophrolaelia, an orchid genus
  • Special linear group, a term used in mathematics, denoted SLn
  • Sine lemniscate function in mathematics
  • Standard length, a commonly used measurement for fish: the length from tip of the snout to the posterior end of the last vertebra

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