cavity
Americannoun
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any hollow place; hollow.
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Anatomy. a hollow space within the body, an organ, a bone, etc.
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a hollow space or a pit in a tooth, most commonly produced by caries. A cavity may be artificially made to support dental restorations.
noun
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a hollow space; hole
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dentistry a soft decayed area on a tooth See caries
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any empty or hollow space within the body
the oral cavity
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electronics See cavity resonator
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A hollow; a hole.
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A hollow area within the body.
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A pitted area in a tooth caused by caries.
Usage
What is a cavity? A cavity is a pit or hole in a tooth caused by the decay of the enamel and bone, such as you might get if you don’t brush your teeth regularly. A cavity is more generally any hollow place or crater, as in When the old building was torn down, all that was left was a huge cavity in the ground. A cavity is also any other hole, divet, or pit in the body, such as the spinal cavity, which surrounds your spinal cord. Example: That cavity in your molar is probably from all the soda you drink.
Synonym Usage
See hole.
Other Word Forms
Etymology
Origin of cavity
First recorded in 1535–45; from Middle French cavite from Late Latin cavitās “hollowness,” equivalent to Latin cav(us) “hollow” + -itās -ity
Explanation
A cavity is a carved-out space inside something solid like a wall or a tooth. If you have a cavity, you have a hole in your tooth, and it’s time to go to the dentist for a filling. Lucky you. Doctors sometimes refer to various internal body parts as cavities, such as the "abdominal cavity," which includes the stomach and other hollow parts of the abdomen. You are more likely to hear the word at the dentist’s office, when she finds a cavity, which is a space in your tooth that's been eaten away by decay. Fun! (Not.) Cavity shares the Latin root cavus, "hollow," with the word cave.
Vocabulary lists containing cavity
There's No There There: Synonyms for "Empty"
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Sounder
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And Then, Boom!
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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.
The researchers created a revised model that combines two important factors: the rapid evolution of light inside the laser cavity and the slower changes occurring in the laser's energy supply.
From Science Daily • May 21, 2026
As Twain later recalled, he was informed that there was a striking cavity in one particular region of his brain, indicating “a total absence of the sense of humor.”
From The Wall Street Journal • Apr. 29, 2026
Pinto said the swelling was caused by a large quantity of both fat and ascites, an abnormal buildup of fluid in the abdominal cavity often linked to cirrhosis of the liver.
From Barron's • Apr. 23, 2026
This provided direct evidence of costal aspiration breathing, where muscles between the ribs expand and compress the chest cavity to pull air into the lungs.
From Science Daily • Apr. 23, 2026
I found their cold little bodies under bushes and one stiff chickadee in a cavity.
From "My Side of the Mountain" by Jean Craighead George
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.
