NOR
The Boolean function which is true if none of its inputs are true and false otherwise, the logical complement of inclusive OR. The binary (two-input) NOR function can be defined (written as an infix operator):
A NOR B = NOT (A OR B) = (NOT A) AND (NOT B)
Its truth table is:
A | B | A NOR B --+---+--------- F | F | T F | T | F T | F | F T | T | F
NOR, like NAND, forms a complete set of Boolean functions on its own since it can be used to make NOT, AND, OR and any other Boolean function:
NOT A = A NOR A
A OR B = NOT (A NOR B)
A AND B = (NOT A) NOR (NOT B)