What’s a good antonym for “disgruntled”? “Happy”? Not descriptive enough. At least that’s what someone in the 1930s must have thought when they came up with “gruntled” as a back-formation of “gruntled.” A back-formation is the creation of a new word, usually by removing a prefix or suffix, from an already existing one. Use the adjective “gruntled” to replace “pleased,” “satisfied,” “contented,” “grateful,” “thankful,” “thrilled,” or any of the other antonyms for “disgruntled.”