ultrathin

adjective

ul·​tra·​thin ˌəl-trə-ˈthin 

: extremely or extraordinarily thin

ultrathin phones

ultrathin fashion models

The molecules ride on the surface like a film of soap and assemble themselves into an ultrathin layer about one-millionth of an inch thick.

—Mike May

Synonyms of ultrathin

• thin
• slender
• narrow

Examples of ultrathin in a Sentence

a new generation of flat-panel TVs that were ultrathin

Recent Examples on the Web

The system is based on a highly compact and flexible ultrathin soft solar blanket that acts as the collection panel and can unroll once the satellite reaches orbit. —New Atlas, 2 Dec. 2025

Things heated up further when the sport and luxury brands turned to the 530 style, which Miu Miu wanted to trim down with an ultrathin sole: enter the 530 SL. —Jaden Thompson, Footwear News, 2 Dec. 2025

The team has created an ultrathin metasurface device that boosts nonlinear optical effects at the nanoscale. —Aamir Khollam, Interesting Engineering, 21 Nov. 2025

The departure adds to mounting challenges for the ultrathin device, which has struggled with disappointing sales since its September launch. —Dave Smith, Fortune, 18 Nov. 2025

Word History

First Known Use

1851, in the meaning defined above

Medical Definition

ultrathin

adjective

ul·​tra·​thin ˌəl-trə-ˈthin 

: exceedingly thin

ultrathin sections for use in electron microscopy