femtosecond

noun

fem·​to·​sec·​ond ˈfem(p)-tə-ˌse-kənd 

-kənt, 

-tō-

: one quadrillionth of a second

Examples of femtosecond in a Sentence

Recent Examples on the Web

For reference, one femtosecond is equal to a one quadrillionth of a second. — Georgina Jedikovska, Interesting Engineering, 29 Oct. 2026

That’s like trying to measure a 100-meter Olympic race on a femtosecond timescale. — Philipp Strasberg, Scientific American, 20 Oct. 2026

The authors calculate that the transition from reflective to transmission needs to take place in about 10 femtoseconds (a femtosecond is 10-15 s), which is insufficient time to move a physical mirror. — Chris Lee, ArsTechnica, 22 July 2026

The new prototype, still very far from being practical, took femtoseconds (quadrillionths of a second) to charge and stored the energy for nanoseconds. — New Atlas, 4 Apr. 2026

Word History

First Known Use

1976, in the meaning defined above

Rhymes for femtosecond

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