OWL is an acronym for: * Web Ontology Language, a markup language for publishing and sharing data using ontologies on the World Wide Web.* Overwhelmingly Large Telescope, a proposed optical telescope that would use a 100-meter-diameter main reflector.* Object Windows Library, an object-oriented software framework for creating Microsoft Windows applications, created by Borland.* Ordinary Wizarding Level, a test of magical aptitude in the fictional Harry Potter series.