STL may refer to:

In International law
  • Special Tribunal for Lebanon
In communications
  • Standard telegraph level
  • Studio/transmitter link
  • Small transmitting loop antenna (a.k.a. magnetic loop)
In geography
  • St. Louis, Missouri, USA
In music
  • Stella Mwangi, a Norwegian-Kenyan singer also known as STL
In software
  • Standard Template Library (for C++)
  • State logic, a PLC programming language
  • Subtitling data exchange format, a subtitling format defined by EBU
  • STL (file format), a file format used to represent 3D CAD models in stereolithography and other solid freeform fabrication technologies
  • Statement List, programming language for Siemens SIMATIC S7
In sports
  • St. Louis Cardinals baseball franchise
  • St. Louis Rams football franchise in the NFL
  • St. Louis Blues, a hockey franchise in the NHL
In transportation
  • Lambert-St. Louis International Airport (IATA airport code: STL)
  • Société de transport de Laval, public transit in Laval, QC Canada
  • Société de transport de Lévis, public transit in Lévis QC Canada
  • Réseau de transport de Longueuil, sometimes erroneously called the Societe de transport de Longueuil, or STL
Other meanings
  • Send the Light
  • Slime Time Live, television series that aired on Nickelodeon from 2000 to 2003
  • Space Technology Laboratories, a former division/subsidiary of the Ramo-Wooldridge Corporation, later TRW Inc, taken over by Northrop Grumman in 2002
  • Standard Telecommunication Laboratories, a research institution famous for developing optical fibre in the 1960s
  • Signal Temporal Logic, a temporal logic based on MITL logic
  • Submerged Turret Loading
  • Licentiate of Sacred Theology