Unintroduced is a word that refers to someone or something that is not yet known or familiar to someone else. There are various synonyms for this word that can help you better express the concept you're trying to convey. These include phrases like unacquainted, unfamiliar, unacclimatized, unversed, uninitiated, and unexperienced. Depending on the context in which you're using this word, you might also want to use other synonyms like untested, undiscovered, uncharted, or unexplored. By using these different synonyms, you can add more depth and nuance to your writing and better convey the meaning you're trying to express.