Stabbings and explosions

[Aegon]

Wrong, wrong and wrong.

Terrorism is the use of violence and intimidation in the pursuit of political goals. The fact that someone blew up a bomb intentionally doesn't tell anything about their motives for doing so, so we cannot establish whether it was terrorism or not as of yet.

Not necessarily. It depends upon the laws and how they are written in the country one resides in. Terrorism, whether foreign or domestic, is the act of causing terror or harm to a person or persons.

For example, the Pennsylvania Consolidated Code Of Statutes, Title 18 subsection 2706 defines it in the following way:
    § 2706.  Terroristic threats.
       (a)  Offense defined.--A person commits the crime of
    terroristic threats if the person communicates, either directly
    or indirectly, a threat to:
           (1)  commit any crime of violence with intent to
       terrorize another;
           (2)  cause evacuation of a building, place of assembly or
       facility of public transportation; or
           (3)  otherwise cause serious public inconvenience, or
       cause terror or serious public inconvenience with reckless
       disregard of the risk of causing such terror or
       inconvenience.

So you see, not all acts of terrorism are political in nature.

"Terroristic threats" is not "terrorism". "Terrorism" is an international academic term that I defined in the post above, "terroristic threats" are just a way that state courts can impose criminal liability. They have two distinct purposes; one is used to try and study and explain the phenomena of violent resistance, while the other exists solely for legal purposes.