From The Free On-line Dictionary of Computing (19 January 2023):
NOR
Not OR.
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)
(1995-02-06)