Un-pretentiously is a word that describes something that is genuine or sincere, free from any kind of pretense or deceit. Its antonyms, on the other hand, are words that describe something that is artificial or contrived, something that's not real or authentic. Some of these antonyms include the words pretentiously, affectedly, insincerely, and disingenuously. When we use these words to describe someone or something, we're essentially saying that they're putting on a show, that they're not being honest or genuine. So while un-pretentiously is a positive attribute, its antonyms are negative and should be avoided in most situations.