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

Researchers at the University of Massachusetts Amherst have now built an ultrathin, flexible mesh that can be integrated into living tissue and generate energy from its motion. — Edd Gent, IEEE Spectrum, 29 Oct. 2026

Researchers at the National University of Singapore (NUS) have developed an ultrathin, flexible electronic skin that lights up when touched, revealing exactly where pressure is being applied and how much, sort of like a skin with a screen. — New Atlas, 27 Oct. 2026

It is coated with an ultrathin film of glass or metal, glazed with photosensitive chemicals, and then passed through a lithography machine. — Gideon Lewis-Kraus, New Yorker, 19 Oct. 2026

This ultrathin material can line the inside of slim smartphones, smartwatches, wearable health trackers, and foldable tablets. — Mrigakshi Dixit, Interesting Engineering, 21 Sep. 2026

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