The word "bombest" is a slang term which means something or someone is exceptionally good, outstanding or amazing. So, the antonyms for this word would be terms such as terrible, disappointing, mediocre, average, or unexceptional. The opposite of bombest could be used to describe something that is unremarkable or underwhelming, unimpressive, or just plain bad. While bombest is often used as a positive descriptor, these antonyms offer a more critical viewpoint. Regardless of the adjective used, it's important to remember that opinions are subjective and what may be bombest to one person, may not be to another.