The antonyms for the phrase "frowning upon" are "approving of", "endorsing", "encouraging", "embracing", "accepting", "welcoming", "praising" and "glorifying". These words represent the opposite of frowning upon, which is to show approval, support, and encouragement towards something or someone. Embracing and accepting, which means to welcome someone or something with open arms, is an antonym that is commonly used when referring to issues of social acceptance or inclusivity. Approving of and praising are also common antonyms for frowning upon, indicating that someone or something is supported, appreciated, and admired.