> AFAIK, in common use the word coup involves the military taking control of the government.
That is one common kind of coup, but distinguished from the broader category. That's why the phrase “military coup” exists to distinguish the kind of coup where the military (or some part of it) is the main actor in seizing control outside of normal bounds.
You’re using a much more narrow definition of what a coup d’état means.
> The sudden overthrow of a government by a usually small group of persons in or previously in positions of authority.
Or to use Wikipedia’s definition
> A coup d'état (French for "blow of state"), often shortened to coup in English (also known as an overthrow), is a seizure and removal of a government and its powers. Typically, it is an illegal seizure of power by a political faction, rebel group, military, or a dictator. Many scholars consider a coup successful when the usurpers seize and hold power for at least seven days.
Yes, the military can be involved in a coup, but the essential definition does not require their involvement. Different terms might be applied if the military is involved, and based on whether or not the military is the primary driver (as in Myanmar) or is backing one side.
That is one common kind of coup, but distinguished from the broader category. That's why the phrase “military coup” exists to distinguish the kind of coup where the military (or some part of it) is the main actor in seizing control outside of normal bounds.