Piehole is a slang term for the mouth, which has become prevalent in American English. However, there are a plethora of synonyms that can be used to replace the word piehole. Some of the common ones include yap, trap, talk hole, gob, maw, muzzle, cakehole, kisser, and chomper. These words have varying degrees of formality, so it's important to choose one that suits the context and audience. Regardless of the synonym used, it's important to remember that using polite language is essential when it comes to good communication. So, while colloquial terms like piehole might be suitable for casual conversations, they may not be appropriate in formal or professional settings.