unknown
adjective
°Not known; unidentified; not well known.
noun
°A variable (usually x, y or z) whose value is to be found.
°Any fact or place about which nothing is known (as in the phrase "into the unknown").
synonyms: anonymous, unfamiliar, uncharted, undiscovered more» , unexplored, unidentified, unnamed, unrecognized, unrevealed, unascertained, obscure, unsung