massless

American  

[mas-lis] / ˈmæs lɪs /

adjective

Physics.

1. pertaining to an elementary particle having zero rest mass, as a photon.

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Other Word Forms

• masslessness noun

Etymology

Origin of massless

First recorded in 1875–80; mass + -less

Example Sentences

Neutrinos are extremely small, nearly massless particles that constantly pass through space, planets, and even our bodies, yet rarely interact with anything.

From Science Daily • Mar. 3, 2026

It’s an esoteric search with very real implications—if just one parameter of the Higgs were positive instead of negative, for instance, atoms would have never formed because massless electrons would never stay in their orbit.

From Scientific American • Aug. 28, 2023

Posting publicly on Twitter, TikTok, YouTube, or Instagram is a lot like using a megaphone to scream to a large, massless, faceless crowd.

From Slate • Nov. 30, 2022

After all, neutrinos have repeatedly surprised physicists, who once assumed that the particles came in only one type and were completely massless and inert.

From Science Magazine • Sep. 28, 2022

The electromagnetic attraction is pictured as being caused by the exchange of large numbers of virtual massless particles of spin 1, called photons.

From "A Brief History of Time: And Other Essays" by Stephen Hawking