The phrase "most augustan" generally refers to something that is grand, majestic, or distinguished. Therefore, antonyms for this phrase would be words that imply something that is insignificant, unimportant, or common. Some antonyms for "most augustan" include ordinary, common, everyday, plain, unremarkable, and unimpressive. Other words that may be used as antonyms for this phrase include lowly, insignificant, and undistinguished. Essentially, any word that denotes the opposite of grand and majestic would be an appropriate antonym for "most augustan.