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