uncertainty principle

noun

: a principle in quantum mechanics: it is impossible to discern simultaneously and with high accuracy both the position and the momentum of a particle (such as an electron)

called also Heisenberg uncertainty principle

Examples of uncertainty principle in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Einstein was never a lover of the randomness that complementarity and the uncertainty principle introduced into the laws of nature. — Keith Cooper, Space.com, 31 July 2025 Batson posed a follow-up question about the uncertainty principle, politely requesting a reply without unwonted nonsense about bananas. — Gideon Lewis-Kraus, New Yorker, 9 Feb. 2026 Importantly, the distance between these two states (alive and dead or up and down) had to be greater than the distance ascribed to the quantum uncertainty principle, which the ETH Zurich scientists confirmed. — Lars Fischer, Scientific American, 12 May 2023 This indeterminism, along with the ambiguity inherent in the uncertainty principle, famously rankled Einstein, who fumed that God doesn’t play dice with the universe. — Zeeya Merali, Discover Magazine, 18 Apr. 2023 Nearly a century after Werner Heisenberg proposed the uncertainty principle, this breakthrough puts the famous concept into direct, real-time observation. — Neetika Walter, Interesting Engineering, 6 Oct. 2025 Based on Heisenberg’s uncertainty principle and the quantum no-cloning theorem, QKD systems theoretically enable unbreakable security. — Vibhu Sharma, Forbes.com, 11 June 2025

Word History

First Known Use

1929, in the meaning defined above

Time Traveler
The first known use of uncertainty principle was in 1929

Rhymes for uncertainty principle

See All Rhymes for uncertainty principle

Browse Nearby Words

uncertainty
uncertainty principle
uncertified
See all Nearby Words

Cite this Entry

“Uncertainty principle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/uncertainty%20principle. Accessed 8 Jul. 2026.

Copy Citation

More from Merriam-Webster on uncertainty principle

Britannica.com: Encyclopedia article about uncertainty principle

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of gambol

See Definitions and Examples »

Popular in Grammar & Usage

See More

Is that lie 'bald-faced' or 'bold-faced'?

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?

Commonly Misspelled Words

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)
See More

Popular in Wordplay

See More

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List

One-Word Oxymorons: Bittersweet, Spendthrift, and More

Ten Words Ending with a Silent ‘T’

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

Is that lie 'bald-faced' or 'bold-faced'?

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
hangman letters and game
Hangman Lightning Round Figure out which word fits in the blanks.
See All