unknown

US /ʌnˈnoʊn/

UK /ʌnˈnoʊn/

1.

not known or familiar

:

•

The cause of the accident is still unknown.

•

She ventured into unknown territory.

:

unfamiliar unidentified unexplored mysterious

:

known familiar

1.

an unknown person or thing

:

•

The letter was sent by an unknown.

•

We are dealing with too many unknowns in this equation.

:

mystery enigma puzzle

:

known familiar