A predicate in logic equivalent to the composition NOT OR that yields
false if any condition is true,
and true if all conditions are false.
NOR is equivalent to , where denotes NOT and denotes OR. In propositional
calculus, the term joint denial is used to refer
to the NOR connective. Notations for NOR include and
(Mendelson 1997, p. 26). The NOR operation is implemented as `Nor`[*A*,
*B*, ...]. The circuit diagram symbol for a NOR gate is illustrated above.

The binary NOR operator has the following truth table (Simpson 1987, p. 547; Mendelson 1997, p. 26).

T | T | F |

T | F | F |

F | T | F |

F | F | T |