I. “+ adjective
Etymology: Middle English unknowen, unknawen, from un- (I) + knowen, knawen known — more at known
1. : not known: as
a. : strange , unfamiliar
b. : not apprehended : not ascertained
c. : incalculable , inexpressible
d. : lacking an established or normal status : having no formal recognition
unknown to the court
2. obsolete : not knowing : ignorant
• un·known·ness noun -es
II. noun
1. : one that is unknown: as
a. : an unknown or unidentified person — usually used with the
the fair unknown
b. : a thing, state, or region that is unknown or imperfectly known or defined
left to seek his fortune in the western unknown
this unknown may alter our plans
2. : something requiring to be discovered, identified, or made clear ; especially : a letter or other symbol in a mathematical equation representing a number that is to be found and often consisting of one of the last letters of the alphabet — see unknown quantity