speed of light

noun phrase

Definition of speed of light

: a fundamental physical constant that is the speed at which electromagnetic radiation propagates in a vacuum and that has a value fixed by international convention of 299,792,458 meters per second symbol c

First Known Use of speed of light

1823, in the meaning defined above

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The first known use of speed of light was in 1823

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Cite this Entry

“Speed of light.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/speed%20of%20light. Accessed 5 Dec. 2020.

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Britannica.com: Encyclopedia article about speed of light

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