The antonyms for the word "nasty-tempered" are several and include affable, amiable, agreeable, charming, cheerful, congenial, cordial, genial, good-humored, good-natured, gracious, mellow, pleasant, and sociable. These words describe individuals who possess a positive and friendly disposition that is far removed from the irritability and bad mood associated with nasty temperaments. An amiable person is generally considered easy to get along with, while a sociable person is outgoing and enjoys being around others. On the other hand, a nasty-tempered person is someone who is prone to anger, aggression, and rudeness, which can be unpleasant to be around.