It looks like an easy question, but what is the definition of «Linguist»? Following to Oxford Dictionary, it’s a person «who knows several foreign languages well» or «who studies languages or linguistics». Regarding the Duden, a linguist is described as «Sprachwissenschaft» and the knowledge of several foreign languages is not mentioned.
Having knowledge of several languages doesn’t automatically make you become a Linguist. It makes clear sense for a Linguist to be able to understand various Languages. It takes something more. For example, to deal scientifically with the origin and connections of different languages and their systematics. You don’t necessarily have to have a scientific background; even laypeople can deal with it and call themselves a linguist.
