The word "foolest" is not a correct English word. However, the closest word to "foolest" could be "foolish." There are many synonyms for foolish, such as silly, absurd, ridiculous, nonsensical, senseless, and unwise. All of these words have the same meaning as foolish and can be used interchangeably. For instance, you could say "It is absurd to believe in conspiracy theories" or "It's unwise to spend all your money on one purchase." Synonyms are an important part of language, and using them can add depth and variety to your writing or speech.