KSI may stand for:* Knight Companion of the Order of the Star of India Key Success Indicator, another name for a key performance indicator Killed or Seriously Injured, used in the field of road safety ksi (unit), kilopound per square inch, a unit of stress or pressure Kontoret för Särskild Inhämtning, Office for Special Assignments, Swedish intelligence agency the IATA code for Kissidougou airport The Icelandic of Football Association of Iceland, KSÍ Kerr Scientific In… (More on Ksi)