attosecond

noun

at·​to·​sec·​ond ˈa-(ˌ)tō-ˌse-kənd How to pronounce attosecond (audio)
-kənt
: one quintillionth (10−18) of a second
An attosecond is to a second what a second is to the age of the universe.IEEE Spectrum

Examples of attosecond in a Sentence

Recent Examples on the Web
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Then, in 2023, the Physics Nobel went to the science of attosecond spectroscopy, which also relies on applications of lasers. Ethan Siegel, Big Think, 7 Aug. 2025 An attosecond is a billionth of a billionth of a second. IEEE Spectrum, 28 May 2024 The shortest pulses produced today are only a few dozen attoseconds long. Will Sullivan, Smithsonian Magazine, 4 Oct. 2023 One attosecond is one-quintillionth of a second, or 0.000000000000000001 seconds. Charlie Wood, Quanta Magazine, 3 Oct. 2023 See All Example Sentences for attosecond

Word History

Etymology

atto- + second entry 4

First Known Use

1962, in the meaning defined above

Time Traveler
The first known use of attosecond was in 1962

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Cite this Entry

“Attosecond.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/attosecond. Accessed 11 Sep. 2025.

Last Updated: - Updated example sentences
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