fluid
Americannoun
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fluids
plural
adjective
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pertaining to a substance that easily changes its shape; capable of flowing.
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consisting of or pertaining to fluids.
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changing readily; shifting; not fixed, stable, or rigid.
fluid movements.
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convertible into cash.
fluid assets.
noun
adjective
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capable of flowing and easily changing shape
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of, concerned with, or using a fluid or fluids
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constantly changing or apt to change
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smooth in shape or movement; flowing
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A state of matter, such as liquid or gas, in which the component particles (generally molecules) can move past one another. Fluids flow easily and conform to the shape of their containers.
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See also state of matter viscosity
Synonym Usage
See liquid.
Other Word Forms
Derived Forms
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fluidnessnoun
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nonfluidnoun
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fluidaladjective
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unfluidadjective
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fluidallyadverb
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fluidlyadverb
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nonfluidlyadverb
Inflected Forms
Nouns
Etymology
Origin of fluid
First recorded in 1595–1605; from Latin fluidus, equivalent to flu(ere) “to flow” + -idus adjective suffix; see -id 4
Explanation
Something that is unstable or subject to change can be described as fluid. The fluid political situation in a particular country makes it unsafe to travel there, with the constant possibility of a violent uprising. A liquid is a fluid — something that flows easily when poured — although gases can also be called fluid. When your doctor told you to drink lots of fluids to help your cold symptoms, she probably meant things like water or orange juice, not root beer floats. If a movement is smooth, it can also be described as fluid. You have to make fluid arm movements in ballet so you look graceful.
Vocabulary lists containing fluid
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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.
See Examples For:
Film schedules can be notoriously fluid, but it's clear that development is well under way, with the director and writer already in place.
From BBC ● Nov. 9, 2026
As a result, a procedure to drain fluid from Isaac's brain did not take place.
From BBC ● Nov. 7, 2026
They collaborated with neurologist Yo-El Ju at Washington University in St. Louis to analyze spinal fluid from a separate group of older adults.
From Science Daily ● Nov. 5, 2026
The chemical maker also warned that conditions in the Middle East will likely remain fluid, and that a potential return to pre-conflict conditions could take longer than anticipated, and follow a non-linear path.
From The Wall Street Journal ● Oct. 30, 2026
“When you start becoming reflective about the process, it undermines your ability. You lose the flow. There are certain kinds of fluid, intuitive, nonverbal kinds of experience that are vulnerable to this process.”
From "Blink" by Malcolm Gladwell
Some experts are worried that the virus -- caught through contact with bodily fluids -- could have spread after the Swiss couple landed back in Nigeria on October 3.
From Barron's ● Oct. 27, 2026
In a follow-up study published in January 2025 in The European Physical Journal E, Trachenko and colleagues examined how fundamental physical constants influence more complicated biological fluids, particularly blood.
From Science Daily ● Oct. 11, 2026
The Ebola virus spreads through contact with infected bodily fluids such as blood or vomit.
From BBC ● Oct. 7, 2026
Humans usually contract it from fleas that have fed on infected wild rodents, or sometimes by handling the tissue or body fluids of a diseased animal, according to the U.S.
From The Wall Street Journal ● Oct. 6, 2026
Others immersed the carcasses in long vats of salt water murky with the blood and fluids of the cattle that had come before them.
From "The City Beautiful" by Aden Polydoros
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Get a wordDefinitions 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.
