microsphere

noun

mi·​cro·​sphere ˈmī-krə-ˌsfir 

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

ˌmī-krə-ˈsfir-i-kəl 

-ˈsfer-

adjective

Examples of microsphere in a Sentence

Recent Examples on the Web

This 2024 Best of Beauty winner is spiked with hydrating hyaluronic acid microspheres and firming peptides that quickly melt into a buttery balm texture without leaving behind a greasy sheen. —Annie Blackman, Allure, 24 Mar. 2025

That’s because the ingredients list includes oil-absorbing microspheres that actually absorb surface oils in effort to reduce any excess shine. —Brigitt Earley, Glamour, 14 Mar. 2025

Those months of additional work steered Langer’s development of novel microspheres that could deliver large molecules of medicine directly to tumors. —IEEE Spectrum, 30 Oct. 2024

This luxurious formula comes in 14 versatile shades, each designed to flex across multiple skin tones, and is infused with blurring microspheres for a soft-focus effect. —Daisy Maldonado, Allure, 6 Feb. 2025

Word History

First Known Use

1950, in the meaning defined above

Rhymes for microsphere

• atmosphere
• biosphere
• centromere
• chemosphere
• chromosphere
• hemisphere
• hydrosphere
• lithosphere
• mesosphere
• miserere
• mountaineer
• photosphere

Medical Definition

microsphere

noun

mi·​cro·​sphere -ˌsfir 

: 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