The antonyms for the word "highflown" are simple, plain, unpretentious, low-key, and modest. Simple means something that is easy to understand or uncomplicated. Plain refers to something that is not elaborate, showy or decorative. Unpretentious is the absence of any attempt to impress others or show off. Low-key refers to something that is restrained, low-profile or unobtrusive. Modest means something that is humble or moderate, without a desire to draw attention or praise. Antonyms for highflown are the opposite of the inflated or bombastic manner, typically used to impress others, making them more down-to-earth, and relatable.