Alternative form of NOR
"The system failed to process the request because neither the username nor the password was correct."
A binary operator composite of NOT OR; negation of OR function.
"In his speech, he praised neither justice nor truth but instead promoted corruption and deceit."
And... not (introducing a negative statement, without necessarily following one).
"He did not finish his homework, nor did he study for the test."
The word nor comes from the Middle English nother, which was originally used to mean "neither." Although it looks like a combination of "not" and "or," this is simply how speakers analyzed its sound rather than its actual history.