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nanosecond

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

noun

  1. one billionth of a second. ns, nsec

nanosecond British  
/ ˈnænəʊˌsɛkənd /

noun

  1.  ns.  one thousand-millionth of a second

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
nanosecond Scientific  
/ năn′ə-sĕk′ənd /

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

nanosecond Cultural  

  1. A billionth of a second.

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

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

From The Wall Street Journal • Dec. 16, 2025

Every metre of distance between two chips adds a nanosecond, one billionth of a second, to the processing time.

From BBC • Sep. 22, 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

In addition, the chip performs key computations in less than half a nanosecond.

From Science Daily • Dec. 2, 2024

If they faced inside the chain, they would repel each other, forcing the molecule to fly apart in a nanosecond.

From "The Gene" by Siddhartha Mukherjee

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.