Citing Wikipedia [1]
> The use of violence or of the threat of violence in the pursuit of political, religious, ideological or social objectives
One could argue these are all political. In the end, you can deduce anything to being political.
Or this definition by Alex P. Schmid from 1988:
> "Terrorism is an anxiety-inspiring method of repeated violent action, employed by (semi-)clandestine individual, group, or state actors, for idiosyncratic, criminal, or political reasons, whereby—in contrast to assassination—the direct targets of violence are not the main targets. The immediate human victims of violence are generally chosen randomly (targets of opportunity) or selectively (representative or symbolic targets) from a target population, and serve as message generators. Threat- and violence-based communication processes between terrorist (organization), (imperiled) victims, and main targets are used to manipulate the main target (audience(s), turning it into a target of terror, a target of demands, or a target of attention, depending on whether intimidation, coercion, or propaganda is primarily sought".
Source and more scholar definitions see [2].
For in-depth criteria I can recommend Alex P. Schmid's "Revised Academic Consensus Definition of Terrorism" from 2011 [3] as it is what scholars at Leiden University use.
Regarding the criterium is it always political, see #9:
> 9. While showing similarities with methods employed by organized crime as well as those found in war crimes, terrorist violence is predominantly political – usually in its motivation but nearly always in its societal repercussions;
(Its too large to quote all 12 criteria; again, please see [3] (no HTTPS))
Sometimes, the goal of ransomware is political, but its disguised as if goal is financial. This provides cover for e.g. a state actor.
[1] https://en.wikipedia.org/wiki/Definition_of_terrorism
[2] https://en.wikipedia.org/wiki/Definition_of_terrorism#Schola...
[3] http://www.terrorismanalysts.com/pt/index.php/pot/article/vi...