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

And yet the core of any successful military operation remains unclear and undefined — what is the objective? —Fareed Zakaria, Washington Post, 27 Feb. 2026

Masataka Yoshida indicated on Saturday that his lack of production and undefined role with the Boston Red Sox has been wearing on him. —Jen McCaffrey, New York Times, 14 Feb. 2026

There was a joy in not knowing what came next, in stepping into something undefined. —Alisa Bittner, Refinery29, 12 Feb. 2026

The judge ruled that an investigator’s misleading testimony to a grand jury, and undefined language in the license fee plan, had compromised the charges against Kilkelly. —Clifford Ward, Chicago Tribune, 11 Feb. 2026

Word History

First Known Use

1611, in the meaning defined above

Rhymes for undefined

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