unknown: Meaning and Definition of

un•known

1. not known; not within the range of one's knowledge, experience, or understanding; strange; unfamiliar.
2. not discovered, explored, identified, or ascertained: the unknown parts of Antarctica.
3. not widely known; not famous; obscure: an unknown writer.

1. a thing, influence, area, factor, or person that is unknown: the many unknowns in modern medicine; The director cast an unknown in the leading role.
2. a 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.