nanosecond

American  

[nan-uh-sek-uhnd, ney-nuh-] / ˈnæn əˌsɛk ənd, ˈneɪ nə- /

noun

1. one billionth of a second. ns, nsec

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nanosecond British  

/ ˈnænəʊˌsɛkənd /

noun

1.  ns.  one thousand-millionth of a second

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nanosecond Scientific  

/ năn′ə-sĕk′ənd /

1. One billionth (10 ^{- 9}) of a second.

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nanosecond Cultural  

1. A billionth of a second.

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Discover More

The term is often used to refer to a very short time: “He missed having an accident by nanoseconds.”

Etymology

Origin of nanosecond

First recorded in 1955–60; nano- + second ²

Explanation

There are one billion nanoseconds in one second. In other words, a nanosecond is one billionth of a second. Even a blink lasts longer than that. One nanosecond compares to a second the same way one second compares to 31.71 years. It's such a tiny amount of time that it's almost impossible to imagine. Some scientists call a nanosecond a "light foot," since light can travel approximately one foot in one nanosecond. You can also use this word figuratively, to mean "a really short length of time." Nano- comes from the Greek root nanos, "a dwarf."

Example Sentences

A nanosecond is the time it takes for light to travel about one foot.

From The Wall Street Journal • Dec. 16, 2025

The first half of the show unpacks the sensory systems that leads people to experience flavor in a nanosecond.

From Salon • Dec. 9, 2024

The intense beams will allow researchers to image samples at nanometer scales and take snapshots of chemical reactions over nanosecond time frames.

From Science Magazine • Nov. 27, 2024

Locating and directing this mission requires extreme precision down to the nanosecond, errors in navigation which could risk spacecraft entering the wrong orbits.

From BBC • Apr. 3, 2024

A second later his face changed back to a smile, a nanosecond flicker.

From "The London Eye Mystery" by Siobhan Dowd

Related Words

• blink of an eye
• millisecond