i use the same definition of the USA government, which is to define terrorism as brown people killing others, especially if they're white people.
Great that the USA and yourself are finally on the same page. Can I have a link to the USA definition? Is it a State Department publication?
Although crazy people certainly cause terror, theirs is a single act of barbarism. "Terrorist'' has come to be defined as an organized group dedicated to furthering their religious or political views by REPEATED cowardly acts of random violence committed in public against random, civilian targets.
Such as the bus bomb in Bulgaria, which I think was planted by a white guy. So maybe he is an exception to your and the US's definition.