carelessness
Americannoun
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failure to pay enough attention to what one is doing; sloppiness.
Unlike unavoidable error, a “mistake” in an experiment is something known to be incorrect due to accident, carelessness, or ineptitude.
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lack of accuracy or thoroughness.
The many instances of carelessness in the book (with references, dates, etc.) detract from its value.
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the fact or quality of being said or done thoughtlessly or negligently.
You were too quick to make promises you can’t possibly fulfill—which only shows the carelessness of your remarks.
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lack of regard or concern for something (usually followed by of, about, for, ortoward ).
He was repulsed by their carelessness and cruelty toward those less fortunate.
Her rudeness and arrogance betray her carelessness for other people's feelings.
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effortless or artless quality.
She is a highly intelligent academic who nevertheless speaks with the simplicity and carelessness of a child.
Other Word Forms
Etymology
Origin of carelessness
First recorded before 1000; careless ( def. ) + -ness ( def. )
Explanation
Acting without thinking things through is carelessness. Don't try to text a friend while you're riding your bike, or your carelessness may send you crashing into a mailbox. You can think of carelessness as negligence, a failure to pay close attention or carefully consider the possible ramifications of your actions. Driver carelessness causes many traffic accidents, and a writer's carelessness can result in grammatical errors and misspellings. The Old English version of this word, carleasnes, meant "freedom from anxiety," something closer to nonchalance than today's carelessness.
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.
No deliberate cruelty wounds this dreamy girl, only carelessness and the cataclysm of her mother’s death, which signals “the last day of childhood.”
From The Wall Street Journal • Mar. 9, 2026
“We want to take immediate action against dangerous drivers before their carelessness leads to a deadly crash,” said Steve Gordon, director of the DMV.
From Los Angeles Times • Dec. 29, 2025
He said the files were accessed due to "carelessness", using passwords shared on messaging apps.
From Barron's • Dec. 17, 2025
It added: "The cyclist had right of way and a moment of carelessness from the driver, by not properly checking the road was clear to cross, has had a life changing impact on the cyclist."
From BBC • Nov. 20, 2025
A moment of carelessness or bad judgment or plain stupidity carried consequences that lasted forever.
From "The Things They Carried" by Tim O'Brien
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.
