UNKNOWN
- one that is not known [n UNKNOWNS]
- not known; not within the range of one's knowledge, experience, or understanding; strange; unfamiliar
- not discovered, explored, identified, or ascertained
- not widely known; not famous; obscure
- thing, influence, area, factor, or person that is unknown
- symbol representing an unknown quantity: in algebra, analysis, etc., frequently represented by a letter from the last part of the alphabet, as x, y, or z