Is terrorism defined by its purpose?
normblog: Terror's victims and the UN: "The Madrid Declaration of 2004 states the matter in a clear way:

'Terrorism is never justifiable... Whatever its form, terrorism is always an unjust and unjustified, cruel, abominable and repulsive crime. It is an affront to the most basic rights of individuals and communities.'

.....
I would like to look at how the most important global organization in the world is dealing with terrorism. I am speaking of the United Nations.

A committee of the United Nations has been trying for the past nine years to write a convention against terrorism. For ordinary people like us, this does not sound like the most difficult thing for lawyers and diplomats to do. We know that terrorism means the deliberate targeting of civilians for injury and death. But there is an international association of states... comprising some 57 countries, nearly 30% of the 191 member states of the United Nations. For nine years, this association has frustrated the writing of the United Nations anti-terror convention by insisting that terrorism must be defined not by the nature of the act but by its purpose."

Murder, too, is defined by its purpose.
Killing can be murder or manslaughter. Maybe terrorism can be, too.

Wasn't the fire-bombing of Dresden partly terrorism?

The terrorists can NOT win without terrorism. This is war.