Google definition?
The fact is that there is no international consensus agreement as to what the definition is among governments, or even entities within the same government. (The FBI and Congress have different definitions.)
Part of the problem, Tombs, is that government acts would be classified as terrorism under your posted definition. Governments don't want that.
Of course their actions are terrorism if they seek to implement political change through terrorizing the people of that nation. One man's "liberators" are another man's terrorists.