STL abbr.
- Licentiate of Sacred Theology
- Sea Train Lines, Inc
- Simulation and Test Language
- Slime Time Live (Nickelodeon)
- Slouching Toward Liverpool
- Societe des Transports de Laval
- Software Tool Library
- Solaris Threading Library (Sun Microsystems API)
- Space Technology Laboratory
- Saint Louis, Missouri, USA - IATA airport code for Lambert-Saint Louis International Airport
- Standard Telegraph Level
- Standard Template Library (for C++)
- Steel
- Stereolithography
- Stockage List
- Store Team Leader (Target stores employee title)
- Strike Team Leader
- studio-transmitter link
- System Threat Library