SL

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 SL_n
• 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