Definition of massless
: having no mass a massless particle
Recent Examples of massless from the Web
Such flavor changing shows that neutrinos cannot be massless.
Models at the time predicted that certain fundamental particles would be massless, but the mechanism that the three physicists proposed explained how these particles could have mass.
Chiao recently performed an experiment in which a photon – a single, massless unit of light energy – was clocked at 1.7 times light speed.
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'massless.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
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