When someone is roused, they have become angry. Something has stirred them until the anger is fully awake — an unfair rule, a rude remark, a crowd that has had enough. You meet this use in stories and in rather careful speech more than in playground talk; a student would usually just say angry or mad. Writers also say roused to anger when they want to show that the feeling was started by something. The word still carries a picture of being shaken out of a quiet state, only here the thing that wakes is temper, not sleep. Though actually, the same spelling is very often just the past of rouse meaning woke or stirred: The noise roused her. This entry is the angry feeling, not the waking up.