What do you call a person who knows 5 languages?

There isn't a specific, universally accepted term for someone who knows 5 languages. However, you could use these descriptions:

* Polyglot: This is the most common term for someone who speaks multiple languages, regardless of the number.

* Pentaglot: This term specifically refers to someone who speaks five languages. However, it's not as widely used as "polyglot."

* Multilingual: This term is used for anyone who speaks more than one language.

* Fluent in five languages: This is a simple and clear way to describe the person.

Ultimately, the best description depends on the context and your preference.