"Inactive" means not active; ""incapable" means not capable; "inseparable" means not separable; and on and on the examples go. It doesn't make sense that "inflammable" means flammable. But we need to keep in mind that it's not always easy to translate one language accurately into another.
I have wondered for decades why the incident in which my great-uncle was murdered is simply called a "disaster" in the popular media, while more recent events are called "massacres," "mass killings," "killing sprees," "mass murders," "rampage killings" and such.
The Republican Party may have dodged a bullet when the FBI announced it had no plans, "at this time," to put the party on its Terrorist Watch List. But some members are none too happy about the slight.