When you're wroth, you're absolutely furious. If you borrow your sister's bike without asking and bend its wheel running into a parked car, don't be surprised if she's completely wroth.
This is an old-fashioned way to say "irate" or "infuriated." Wroth is extremely rare these days, but you may come across it in an old novel. Like its more common cousin, wrath, or "anger," wroth comes from the Old English wrað, "angry, tormented, or twisted."