Definitions for undefinedˌʌn dɪˈfaɪnd
Random House Webster's College Dictionary
not defined or explained.
indefinite in form or extent:
an undefined feeling of sadness.
Origin of undefined:
not precisely limited, determined, or distinguished
"an undefined term"; "undefined authority"; "some undefined sense of excitement"; "vague feelings of sadness"; "a vague uneasiness"
Lacking a definition or value
That does not have a meaning and is thus not assigned an interpretation
The result of division by zero is undefined.