What, I was wondering, is the origin of this word? I understand it was a war cry or order once upon a time. Is it based on "Have...Oc? I dont know what a Oc is but maybe something like that.

According to Oxford, to cry havoc means to call out for devastation.So, to shout for a place to be attacked and ruined. 'havoc' is Anglo Norman for ruin.

That's a pretty interesting definition. It suits it though. It's like telling someone you wreaked havoc in your room trying to find something.

I found a site that says it comes from old French Havot = plunder. Cry Havoc meant permission was given to start looting.

I read somewhere (may have been one of those Shakespere "translations") that "Havoc" ment "No Mercy!" or "No Quarter" and that if your commander cried "havoc!" that no quarter would be given or asked.