observable
American-
A measurable property of a physical system, such as mass or momentum. In quantum mechanics, observables correspond to mathematical operators used in the calculation of measurable quantities. Operators that do not commute, having a nonzero commutator, correspond to observables that cannot be precisely measured at the same time, such as momentum and position.
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See also uncertainty principle
Other Word Forms
Etymology
Origin of observable
1600–10; < Latin observābilis remarkable, equivalent to observā ( re ) to observe + -bilis -ble
Explanation
Something observable can be perceived or detected — you can see it, hear it, or otherwise sense that it's there. An observable change in the temperature outdoors will make you run back in for your hat and gloves. If an observable hush falls over the dining room when your grandfather clears his throat, it's something that everyone notices. Observable differences between you and your twin sister might include different haircuts and the fact that you wear glasses but she doesn't. Observable things can be sensed (perceived with one of your five senses) or intuited.
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.
In some cosmological ideas, everything we call the universe, including regions far beyond our observable horizon, might be only one bubble among potentially countless others.
From Science Daily ● Sep. 28, 2026
The rate that would achieve the Fed’s dual mandate is unknown, interest rates fluctuate with economic performance, and inflationary expectations aren’t observable.
From The Wall Street Journal ● Sep. 14, 2026
They also align with observable warming in the ocean and atmosphere, which are potentially affecting El Niño’s dynamics, he said.
From Los Angeles Times ● Sep. 4, 2026
“Recent retail fuel margin weakness called out by Ampol is readily observable from market data and we agree with management that it’s temporary,” Jefferies says.
From The Wall Street Journal ● Aug. 24, 2026
In fact, the times when she became extremely cheerful for days on end - and for no observable reason - were almost as disturbing to me as her sudden, often prolonged sullen spells.
From "The Remains of the Day" by Kazuo Ishiguro
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.
