undefined

adjective not precisely limited, determined, or distinguished; `an undefined term`; `undefined authority`; `some undefined sense of excitement`; `vague feelings of sadness`; `a vague uneasiness`
Found on https://www.encyclo.co.uk/local/20974

Undefined

[mathematics] In mathematics, the word undefined has several different meanings, depending on the context. See extended real number line for more information. ...
Found on http://en.wikipedia.org/wiki/Undefined_(mathematics)

undefined

an aspect of C++'s semantics for which no reasonable behavior is required. An example is dereferencing a pointer with the value zero. Avoid undefined behavior. See also: implementation defined. TC++PL C.2.
Found on http://www.stroustrup.com/glossary.html

undefined

[adj] - not precisely limited, determined, or distinguished
Found on http://www.webdictionary.co.uk/definition.php?query=undefined
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