undiagnosed

adjective

un·​di·​ag·​nosed ˌən-ˌdī-ig-ˈnōst 

-əg-, 

-zd

: not diagnosed : not identified through diagnosis

an undiagnosed illness

… the symptoms of the syndrome may be subtle and thus may remain undiagnosed.

—Dwight R. Robinson

a condition that often goes undiagnosed

Examples of undiagnosed in a Sentence

Recent Examples on the Web

It’s believed to affect up to 13% of reproductive-age women, but the World Health Organization estimates that most cases — about 70% — go undiagnosed. —Annalisa Merelli, STAT, 1 Apr. 2026

The physicist and optics researcher continued to experience symptoms of her body seemingly unable to keep up with her, going undiagnosed for years. —Literary Hub, 1 Apr. 2026

Many returning veterans brought home physical disabilities; others suffered from undiagnosed post-traumatic stress disorder, which mid-20th-century medical professionals struggled to treat. —The Know, Denver Post, 29 Mar. 2026

Leigh suffered from undiagnosed bipolar disorder, and her mental health was exacerbated by a 1940s miscarriage and Olivier’s rising fame. —Jami Ganz, New York Daily News, 27 Mar. 2026

Word History

First Known Use

1864, in the meaning defined above

Medical Definition

undiagnosed

adjective

un·​di·​ag·​nosed -ˈnōst 

: not diagnosed : eluding diagnosis

undiagnosed disease