definition
Is there an authoritative definition of what a terrorist is?
<p>An intelligent unbiased observer from another galaxy wants to understand the notion of a 'terrorist' because the alien sees:</p>

<p>“One man’s terrorist is another man’s freedom fighter”</p>

<p>Is there an authoritative definition of terrorism that would enable a set of unbiased observers arrive at consistent labeling of terrorism and freedom fighters?</p>

<h2>There is a definition</h2>

<p>Or rather, there are as many definitions as there are jurisdictions who have passed laws about them.</p>

<p>In <a href="/questions/tagged/australia" class="post-tag" title="show questions tagged &#39;australia&#39;" rel="tag">australia</a>, a terrorist is a person who commits a <a href="https://www.ag.gov.au/NationalSecurity/Counterterrorismlaw/Pages/AustraliasCounterTerrorismLaws.aspx" rel="noreferrer">terrorist act</a>.</p>

<blockquote>
  <p>A terrorist act is an act, or a threat to act, that meets both these criteria:</p>
  
  <ul>
  <li><p>it intends to coerce or influence the public or any government by intimidation to advance a political, religious or ideological cause.</p></li>
  <li><p>it causes one or more of the following:</p></li>
  </ul>
  
  <p>◦  death, serious harm or danger to a person</p>
  
  <p>◦  serious damage to property</p>
  
  <p>◦  a serious risk to the health of safety of the public</p>
  
  <p>◦  serious interference with, disruption to, or destruction of critical infrastructure such as a telecommunications or electricity network.</p>
  
  <p>Advocating, protesting, dissenting or taking industrial action are not terrorist acts where the person doing the activity does not intend to cause serious harm to a person or create a serious risk to public safety.</p>
</blockquote>

<p>If the Crown accuses someone of being a terrorist then they have to convince, beyond reasonable doubt, a set of unbiased observers (a jury) that they did these things.</p>

<p>“Freedom fighter” is not a term defined in Australian law so it would take on its normal meaning as someone who fights or otherwise struggles for “freedom” - a word that is so broad and subjective that it would be context dependent. Fighting could range from peaceful protest to armed insurrection. The hypothetical “freedom fighter” might or might not engage in “terrorist acts” so the terms “freedom fighter” and “terrorist” are not mutually exclusive.</p>

<p>The word "terrorist" (or "terrorism") is like any other word of the English language, which means that the notion of an "authoritative" definition is a bit sketchy. One finds definitions in dictionaries, and I suppose an authoritative definition is found in an authoritative dictionary. Your desideratum of an authoritative source precludes using Urbandictionary. Since there is no one <em>official</em> dictionary of English, you would have to go for one of the most respected dictionaries: The Oxford English Dictionary, or Merriam Webster's Third New International dictionary. It would in fact be best to provide both, since this could reveal differences in sources (and what they have in common).</p>

<p>Another approach would be to gather together statutory definitions. This is generally in inferior approach, because it does not correctly say how the word "terrorism" is defined, but if you were explaining to an alien lawyer how we statutorily define "terrorism", then of course you want to point to specific statutes. There are enough Anglophone countries that a comparative study could be interesting. It really depends on why you want to "define" terrorism/t.</p>

<p>At the US federal level, <a href="https://www.law.cornell.edu/uscode/text/18/2331" rel="nofollow noreferrer">"international terrorism"</a> is given a definition, applicable to Title 18. A seeming peculiarity is that the act must</p>

<blockquote>
  <p>occur primarily outside the territorial jurisdiction of the United
  States, or transcend national boundaries in terms of the means by
  which they are accomplished, the persons they appear intended to
  intimidate or coerce, or the locale in which their perpetrators
  operate or seek asylum</p>
</blockquote>

<p>The reason for this is that, unlike many countries, there are federal and state levels of law-making, and under the US Constitution they are supposed to have distinct subject matters (hence regular robbery is not a federal crime). The aliens would have to understand this feature of US law, in order to understand the otherwise "incorrect" clause in the Title 18 definition. There is a different definition of terrorism under <a href="https://www.law.cornell.edu/uscode/text/22/2656f#d_1" rel="nofollow noreferrer">Title 22</a>, pertaining to the obligation of the Sec'y of State to report on terrorism, which is</p>

<blockquote>
  <p>premeditated, politically motivated violence perpetrated against
  noncombatant targets by subnational groups or clandestine agents</p>
</blockquote>

<p>and "international terrorism" is "terrorism involving citizens or the territory of more than 1 country". For purposes of the Attorney General, the <a href="https://ecfr.io/Title-28/pt28.1.0#se28.1.0_15" rel="nofollow noreferrer">Code of Federal Regulations</a> semi-defines terrorism by saying that</p>

<blockquote>
  <p>Terrorism includes the unlawful use of force and violence against
  persons or property to intimidate or coerce a government, the civilian
  population, or any segment thereof, in furtherance of political or
  social objectives</p>
</blockquote>

<p>(Other things could be considered "terrorism", so this is an "at least" definition).</p>

<p>Even though we're on Law.SE, I would not look in law books for definitions of such terms. So,</p>

<blockquote>
  <p>Is there an authoritative definition of terrorism that would enable a set of unbiased observers arrive at consistent labeling of terrorism and freedom fighters?</p>
</blockquote>

<p>Well, with a caveat regarding the authoritativeness of dictionaries and the fluidity and context-sensitivity of language, I'd say "yes, but many people don't like it".</p>

<p>From <a href="https://www.dictionary.com/browse/terrorism?s=t" rel="nofollow noreferrer">Dictionary.com</a>:</p>

<blockquote>
  <p><strong>terrorism</strong> [ ter-uh-riz-uh m ]</p>
  
  <ol>
  <li>The use of violence and threats to intimidate or coerce, especially for political purposes.</li>
  <li>the state of fear and submission produced by terrorism or terrorization.</li>
  <li>a terroristic method of governing or of resisting a government.</li>
  </ol>
</blockquote>

<p>Definitions (2.) and (3.) are derivatives of (1.), so (1.) is your basic definition.</p>

<p>From the <a href="https://www.merriam-webster.com/dictionary/terrorism" rel="nofollow noreferrer">Merriam-Webster dictionary</a>:</p>

<blockquote>
  <p><strong>ter·​ror·​ism</strong> | \ ˈter-ər-ˌi-zəm</p>
  
  <ol>
  <li>the systematic use of terror especially as a means of coercion</li>
  </ol>
</blockquote>

<p>and for "terror", we have (ommitting irrelevant definitions):</p>

<blockquote>
  <p><strong>terror</strong>, noun</p>
  
  <ol>
  <li>a state of intense or overwhelming fear</li>
  <li>violence or the threat of violence used as a weapon of intimidation or
  coercion </li>
  <li>a very frightening or terrifying aspect</li>
  </ol>
</blockquote>

<p>The reason many people won't like it is that it's quite broad. As comments on other definitions indicate, it covers a lot of governmental activity, perhaps to the extent that most world states (including democracies) are ruled in part through terrorism.</p>
