Definitions for "Undefined"
To present participles which come from intransitive verbs, or are themselves employed as adjectives, to mark the absence of the activity, disposition, or condition implied by the participle;
An expression that cannot be given a value without implying a false statement. For instance, 1/0 is undefined, for if 1/0 = , then 0 x = 1 which must be false.
A medium or substance added to medium in which not all of the constituents or their concentrations are chemically defined, such as media containing coconut milk, malt extract, casein hydrolysate, fish emulsion or other complex compounds. cf  organic complex.
not precisely limited, determined, or distinguished; "an undefined term"; "undefined authority"; "some undefined sense of excitement"; "vague feelings of sadness"; "a vague uneasiness"
A special value given to variables after they are created and before a value has been assigned to them.
Having an unpredicatable (and not necessarily valid) value.
primitive value automatically assigned to just-declared variables and formal arguments for which there are no actual arguments.
(adj.) for a data object, the property of not having a determinate value.
adj. Refers to behavior which is not specified by the Standard, for which an implementation is not required to do anything reasonable. Example: the behavior of the expression i = i++. See questions 3.3 and 11.33.