goony adjective 2noun 1forms 5 adjective2 •(slang) Silly, crazy, foolish, stupid, or awkward.After their prank was successful, the friends wore goony smiles on their faces for the rest of the day. •Of or like a goon; thuggish; brutal. noun1 •(informal) a goon; a foolish, stupid, silly, or awkward person. formsgoonies · goonier · more goony · gooniest · most goony