Made content or pleased; the opposite of disgruntled (though extremely rare in actual usage).
Past participle of gruntle, formed by adding -ed. Gruntled exists more as a theoretical word that logically should exist to oppose disgruntled.
People jokingly use 'gruntled' to mean satisfied or pleased, but it's so uncommon that most dictionaries barely acknowledge it—yet language enthusiasts love creating back-formations like this to 'complete' negated words.
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