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.
It is with such acts of carelessness that leaders lose their credibility and empires lose their power.
From Slate • Jun. 1, 2026
Such cases get attention and send a message that carelessness with firearms is serious business.
From Salon • May 22, 2026
“All the mighty, anarchic carelessness of our country was revealed in Borger,” Benton observed.
From The Wall Street Journal • Apr. 24, 2026
Had the ball struck the girl, he would almost certainly have been defaulted and seen another attempt at number 25 aborted by his own carelessness.
From BBC • Jan. 27, 2026
“Anyone who has watched the dusters and sprayers of arsenical insecticides at work must have been impressed by the almost supreme carelessness with which the poisonous substances are dispensed.”
From "Silent Spring" by Rachel Carson
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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.