attosecond

noun

at·​to·​sec·​ond ˈa-(ˌ)tō-ˌse-kənd 

-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

Some very important applications The findings could prove especially important for attosecond science, a field focused on observing electron dynamics over timescales measured in billionths of a billionth of a second. —Christopher McFadden, Interesting Engineering, 31 May 2026

Optical atomic clocks, which use intersecting laser beams to entrap and monitor the atoms, are currently accurate down to 1 attosecond, or a billionth of a billionth of a second. —IEEE Spectrum, 20 Dec. 2025

An attosecond is to one second about what one second is to the 14 billion-year age of the universe. —Thomas Linker, The Conversation, 15 Oct. 2025

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

Word History

Etymology

atto- + second entry 4

First Known Use

1962, in the meaning defined above

Rhymes for attosecond

• femtosecond
• microsecond
• millisecond
• nanosecond
• picosecond
• beckoned
• reckoned
• second
• seconde