undefined

adjective

un·​de·​fined ˌən-di-ˈfīnd 

: not defined: such as

a

: not clearly or precisely shown, described, or limited

undefined rules

undefined powers

a vague, undefined feeling of dread

… the true outlines of Clinton's foreign policy remain undefined.

—William Greider

b

: not provided with a definition

an undefined dictionary entry

Synonyms of undefined

• vague
• faint

Examples of undefined in a Sentence

plagued by undefined worries that kept her awake at night

Recent Examples on the Web

The top players’ form is patchy or simply undefined. — Ava Wallace, New York Times, 27 June 2026

The bodies float in an undefined space, at once intimate and strangely cosmic. — George Nelson, ARTnews.com, 8 May 2026

Those that hand a broken or undefined process to an agent typically get faster, more consistent failures. — Rhett Power, Forbes.com, 7 June 2026

Well, the Thirteenth Amendment left the country with 4 million freed slaves, undefined. — David Frum, The Atlantic, 10 June 2026

Word History

First Known Use

1611, in the meaning defined above

Rhymes for undefined

• aligned
• alined
• assigned
• behind
• combined
• confined
• consigned
• crosswind
• declined
• defined
• designed
• divined