A passive speaker (also referred to as a receptive bilingual or passive bilingual) is a category of speaker who has had enough exposure to a language in childhood to have a native-like comprehension of it, but has little or no active command of it.[1] Passive fluency is often brought about by being raised in one language (which becomes the person's passive language) and being schooled in another language (which becomes the person's native language).[2][3]
I didn't know there was a term for this! It is sort of contradictory, though, as the passive speaker doesn't speak much.