LTI can refer to:LTI – Lingua Tertii Imperii, a book by Victor Klemperer Language Technologies Institute, a division of Carnegie Mellon University Linear time-invariant system, an engineering theory that investigates the response of a linear, time-invariant system to an arbitrary input signal Licensed to Ill, the 1986 debut album by the Beastie Boys Lost Time Incident or industrial injury or Occupational injury Learning Tools Interoperability Louisiana Training Institute-East Baton Rouge, later known as the Jetson Center for Youth (JCY), a juvenile prison in Louisiana