Initialism of slower than light, sublumic, relativistically moving slower than the speed of light in the void.
"The astrophysicist dismissed the claim as scientific fantasy because it proposed a propulsion system capable of accelerating an STL drive to speeds exceeding that of photons."
"The stl report was ready before lunch."
Abbreviation of St. Louis. (Saint Louis)
"The STL Cardinals played their home game at Busch Stadium."