Unknown
/ʌnˈnəʊn/
verb
To undo the process of knowing, to lose knowledge of something.
noun
A variable (usually x, y or z) whose value is to be found.
Any thing, place, or situation about which nothing is known; an unknown fact or piece of information.
A person of no identity; a nonentity
adjective
(sometimes postpositive) Not known; unidentified; not well known.
Synonyms: anonymous, obscure, unascertained, uncharted, undiscovered, unexplored, unfamiliar, unidentified