mi·​cro·​sphere ˈmī-krə-ˌsfir How to pronounce microsphere (audio)
plural microspheres
: a tiny solid or hollow sphere (as of glass, ceramic, or polymer) that is 1 to 1000 micrometers in diameter and that is used in industrial and consumer products and in biomedical applications (such as drug delivery or diagnostic imaging)
The idea is to package protein drugs into microspheres. From a single injection under the skin the drug is released at a slow and steady rate over a long period.Michael Gianturco
With microspheres, boat bumpers are more buoyant and cosmetics silky smooth. Drugs become more effective and paints more stain resistant. Microspheres are even responsible for the smell of scratch-and-sniff stickers.Rachel Ross
A microsphere is not the same as a microparticle, because microparticle is a general term that refers only to the size of the granular material and does not provide information on the shape. Microspheres are always round and spherical.Cynthia A. Gosselin
… a gas-filled synthetic polymer microsphere that enhances the detection of blood flow within the heart muscle in echocardiograms …Kelly Holman
microspherical adjective

Examples of microsphere in a Sentence

Recent Examples on the Web That’s because the ingredients list includes oil-absorbing microspheres that actually absorb surface oils in effort to reduce any excess shine. Glamour, 29 Mar. 2024 The products contain hyaluronic acid microspheres to help smooth fine lines and wrinkles, along with a peptide complex to enhance youthful skin, fatty acids to help protect and restore, and collagen stabilizer to help moisturize and provide a smoothing effect. Dahvi Shira, Forbes, 28 Mar. 2024 The retinol is encapsulated in botanical microspheres for gradual release, mitigating redness and irritation while also infusing skin with the calming antioxidant properties of edelweiss. Mary Honkus, Glamour, 27 Feb. 2024 In fact, the ingredients list boasts oil-absorbing microspheres that work to absorb surface oils and reduce excess shine—key in the blazing heat. Brigitt Earley, Glamour, 13 Feb. 2024 Most of their bulk comes from blocks of syntactic foam—a buoyant, crush-resistant material made of glass microspheres in epoxy resin—that are padded around the frame. Susan Casey, Smithsonian Magazine, 9 Aug. 2023 Physicists described the salinity staircase of the Arctic Ocean, where glass microspheres will only further melt sea ice, and where the number of rainy days is predicted to double by 2100. Matthew Gavin Frank, Harper's Magazine, 21 Dec. 2022 The back half of the sub holds blocks of a buoyant material called syntactic foam, composed of hollow glass microspheres embedded in an epoxy matrix; the newest type of this material can stand up to the deepest sea pressures. Eliza Strickland, IEEE Spectrum, 29 Feb. 2012 The microsphere, buffeted by Brownian motion, rolls along the trail picking up one peptide after another. The Physics Arxiv Blog, Discover Magazine, 23 Sep. 2021

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'microsphere.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1950, in the meaning defined above

Time Traveler
The first known use of microsphere was in 1950

Dictionary Entries Near microsphere

Cite this Entry

“Microsphere.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/microsphere. Accessed 21 Jul. 2024.

Medical Definition


mi·​cro·​sphere -ˌsfir How to pronounce microsphere (audio)
: a spherical shell that is usually made of a biodegradable or resorbable plastic polymer, that has a very small diameter usually in the micron or nanometer range, and that is often filled with a substance (as a drug or antibody) for release as the shell is degraded

More from Merriam-Webster on microsphere

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!