In colloquial language, nil as an abbreviation of the Latin word "nihil" (nothing) is sometimes used to express disagreement.
In some computer programming languages, nil is used to indicate an invalid or uninitialized variable (see also Null). In this context it was first used in the LISP programming language and is an abbreviation for "not in list".
There is also a mock programming language called Nil which is in fact a technical joke. Here the word seems to derive from Nihilism.
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