If and how you apply the terrorism label depends on who you are and what your purpose is. For example, many in the American Muslim community object that only events linked to "radical Islam" are labeled as terrorism by politicians and the media while attacks by white supremacists and neo-Nazis, such as the 2015 mass shooting at the historic black church in Charleston, South Carolina are not.
There is no standard definition of terrorism. Some organizations that are not necessarily terrorist groups, but on the verge of terrorism include Animal Liberation Front, Army of God, Black Liberation Army, and The Jewish Defense League.