Here are some options you could use:
In French:
* Un locuteur natif: This literally means "a native speaker," and it's the most accurate way to describe someone who grew up speaking French.
* Un francophone: This means "a French speaker" and can be used to describe anyone who speaks French, regardless of their native language.
* Quelqu'un qui parle couramment français: This literally means "someone who speaks French fluently" and is a more specific way to describe someone with advanced French skills.
In English:
* Fluent French speaker: This is the most straightforward way to describe someone who speaks French fluently.
* Native French speaker: This indicates that French is their first language.
* Proficient French speaker: This implies a high level of skill in French.
You could also use more descriptive phrases like:
* Someone who speaks French like a native.
* Someone who is highly proficient in French.
* Someone who has a strong command of the French language.
Ultimately, the best way to describe a fluent French speaker depends on the context and the specific level of fluency you want to emphasize.