* Polyglot: This is the most common term for someone who speaks multiple languages.
* Octoglot: This word specifically means someone who speaks eight languages. It's not as common as "polyglot" but more specific.
* Hyperpolyglot: This term is used for someone who speaks 6 or more languages fluently. While not directly referring to eight languages, it still highlights the impressive level of multilingualism.
You can also simply say:
* They are fluent in eight languages.
* They speak eight languages fluently.
Ultimately, the best way to describe someone who speaks eight languages fluently depends on the context and your personal preference.