The term I heard for this is “state terrorism”.

The actions speak for themselves and how established or not the power of the actors doing the deed is, has no relevance for the moral quality of such actions.

Using different language is a trap put in place by those in established power - it segregates what morally are the same kind of acts into two groups, by how established the power of those doing the deeds are, and the acts of the well established power are relentlessly portrayed using those special separate designations as if they had a morally different character - ann acceptable one - than the exact same acts when committed by those outside established power structures.

This is why, say, when an Israeli soldier shoots on the head a child throwing stones at an armored digger, it’s not designated in the media as “murder” or even “terrorism” even though from a strict “taking no sides” judicial point of view it is definitelly the former and depending on intention might very well be the latter.

So yeah, murder for the purpose of scaring the rest is terrorism, no matter if those doing the deeds are part of a well established power structure, called “soldiers” and using 500lb bombs dropped from military planes that cost many millions of dollars or part of a group which is not a well established power structure, called “rebels” and using knifes - the means and how well entrenched the power structure behind the acts is are both irrelevant for the dtermining the moral quality of that deed.