Undefined

adj, noun

adj, noun ·3 syllables ·Moderate ·High school level

Definitions

Noun
  1. 1
    An undefined value.

    "[Option:] · [PDP11:] F [BSD:] · [XE 2.3:] [1] [XE 3.0:] · [SIII:] · [COFF:] · [meaning:] make undefineds global"

Adjective
  1. 1
    Lacking a definition or value. not-comparable

    "We slid into our office, past two women discussing the "X factor," an apparently undefined quality their firm felt they lacked."

  2. 2
    That does not have a meaning and is thus not assigned an interpretation. not-comparable

    "The result of division by zero is undefined."

Adjective
  1. 1
    not precisely limited, determined, or distinguished wordnet

Synonyms

All synonyms
indefinablemysteriousaleatoricaleatoryall powerfulall seeing

Example

More examples

"If you divide any number by zero, the result is undefined."

Etymology

From un- + defined.

Related phrases

undefined behavior

More for "undefined"

SynonymsSentencesPronunciationTranslate

Next best steps

Find stronger synonymsSee usage examplesCheck pronunciationBrowse writing guides

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.