The condition of being unknown

(obsolete) Not acknowledged or recognised.

The lack or absence of knowledge.

(idiomatic) A person or thing whose nature or value is a mystery. / Used other than figuratively or idiomatically: see unknown, quantity.

An uncertainty of unknown magnitude, consequence, structure, and probability characteristics, possibly with completely unsuspected existence; something that we don't know that we don't know.

plural of unknown unknown

plural of unknown quantity

The quality of not knowing; ignorance of something.

a phone number (on a phone call) that is unfamiliar to the recipient / a hidden number; a phone number that is hidden from the recipient

Synonym of as-yet-unknown