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
Mike MayExamples of ultrathin in a Sentence
a new generation of flat-panel TVs that were ultrathin
Recent Examples on the Web
Recently, Korean researchers developed an ultrathin silver-ion coating that prevents dendrite formation in lithium-metal batteries, improving safety, lifespan, and commercialization potential for next-generation energy storage.
—Jijo Malayil, Interesting Engineering, 25 Oct. 2025
This iconic brow pencil is well-loved in the industry (and in the Allure office) for its ultrathin, retractable tube—no sharpener needed—and its ability to easily shape and fill in sparse sections with hair-like strokes.
—Sarah Kinonen, Allure, 1 Oct. 2025
Along with an ultrathin iPhone Air and other redesigns, the new phones come with a less flashy upgrade that could turn out to be the true killer feature.
—Lily Hay Newman, Wired News, 11 Sep. 2025
The Air, starting at $999, has an ultrathin design that is just 5.6 millimeters thick, about 28% thinner than the standard iPhone 16.
—Todd Spangler, Variety, 9 Sep. 2025
See All Example Sentences for ultrathin
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Jijo Malayil, Interesting Engineering, 25 Oct. 2025
This iconic brow pencil is well-loved in the industry (and in the Allure office) for its ultrathin, retractable tube—no sharpener needed—and its ability to easily shape and fill in sparse sections with hair-like strokes.
—Sarah Kinonen, Allure, 1 Oct. 2025
Along with an ultrathin iPhone Air and other redesigns, the new phones come with a less flashy upgrade that could turn out to be the true killer feature.
—Lily Hay Newman, Wired News, 11 Sep. 2025
The Air, starting at $999, has an ultrathin design that is just 5.6 millimeters thick, about 28% thinner than the standard iPhone 16.
—Todd Spangler, Variety, 9 Sep. 2025
See All Example Sentences for ultrathin
Cite this Entry
“Ultrathin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ultrathin. Accessed 3 Nov. 2025.
Copy CitationMedical Definition
ultrathin
adjective
ul·tra·thin
ˌəl-trə-ˈthin
: exceedingly thin
ultrathin sections for use in electron microscopy
Love words? Need even more definitions?
Merriam-Webster unabridged
Share