There is no universal agreement on the legal
definition of terrorism,   although there exists a  consensus academic definition created by scholars.
legal systems and government agencies use different definitions of terrorism, and governments have been reluctant to formulate an agreed-upon a legally binding definition. Difficulties arise from the fact that the term has become politically and emotionally charged. A simple definition proposed to the  United Nations Commission on Crime Prevention and Criminal Justice (CCPCJ) by terrorism studies scholar Alex P. Schmid in 1992, based on the already internationally accepted definition of war crimes, as "peacetime equivalents of war crimes", was not accepted.  
Scholars have worked on creating various academic definitions, reaching a
consensus definition published by Schmid and A. J. Jongman in 1988, with a longer revised version published by Schmid in 2011, some years after he had written that "the price for consensus [had] led to a reduction of complexity". 
United Nations General Assembly condemned terrorist acts by using the following political description of terrorism in December 1994 (GA Res. 49/60):
Criminal acts intended or calculated to provoke a state of terror in the general public, a group of persons or particular persons for political purposes are in any circumstance
unjustifiable, whatever the considerations of a political, philosophical, ideological, racial, ethnic, religious or any other nature that may be invoked to justify them.
United States of America, terrorism is defined in Title 22 Chapter 38, of the U.S. Code as "premeditated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents".
Williamson, Myra (2009). . Ashgate Publishing. p. 38. Terrorism, war and international law: the legality of the use of force against Really aj 2001 ISBN . 978-0-7546-7403-0
Schmid, Alex P. (2011). "The Definition of Terrorism". The Routledge Handbook of Terrorism Research. Routledge. p. 39. ISBN . 978-0-203-82873-1
Frampton, Martyn (2021), English, Richard (ed.), "History and the Definition of Terrorism", The Cambridge History of Terrorism, Cambridge: Cambridge University Press, pp. 31–57, ISBN 978-1-108-66262-8 , retrieved May 11, 2021
^ a b c Cite error: The named reference
routledgehandbk2011 was invoked but never defined (see the
^ Hoffman (1998), p. 23, See
the 1 Nov 1998 review by Raymond Bonner in of The New York Times Inside Terrorism
Siegel, Larry (January 2, 2008). . Cengage Learning. Criminology ISBN 9780495391029 . Retrieved . November 27, 2015
Schmid, Alex P. (October 7, 2020). Brunton, Gillian; Wilson, Tim (eds.). Issue title: Terrorism: Its Past, Present & Future Study - A Special Issue to Commemorate CSTPV at 25. "Discussion 1 - Revisiting the wicked problem of defining terrorism". . Contemporary Voices: St Andrews Journal of International Relations 1 (1). doi: . 10.15664/jtr.1601 ISSN 2516-3159. Text may have been copied from this source, which is available under a Attribution 4.0 International (CC BY 4.0) licence. (Per this page.
Schmid, Alex P. (2004). "Terrorism - The Definitional Problem". . Case Western Reserve Journal of International Law 36 (2) . Retrieved – via April 9, 2021 Case Western Reserve University School of Law.
United Nations General Assembly (December 9, 1994). "49/60: Measures to Eliminate International Terrorism". UN Doc. A/Res/60/49. Archived from the original on June 16, 2019. The General Assembly, Recalling its resolution 46/51 of 9 December 1991 and its decision 48/411 of 9 December 1993,... Annex: Declaration on Measures to Eliminate International Terrorism
"22 U.S. Code § 2656f - Annual country reports on terrorism". LII / Legal Information Institute . Retrieved . March 10, 2019