The term 'linguistically knowledgeable' can be described as someone who is FLUENT in language. This person has a deep understanding of the structure, grammar, and syntax of language. They are able to communicate effectively in multiple languages and have a strong grasp of the nuances of each language. They are also able to recognize and understand the cultural implications of language. This person is well-versed in the history and evolution of language, and is able to apply this knowledge to their work.