LTI

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

Companies

 * London Taxis International
 * Larsen & Toubro Infotech

Biology and medicine

 * Lymphoid tissue-inducer cell, see innate lymphoid cells