carelessness

American  

[kair-lis-nis] / ˈkɛər lɪs nɪs /

noun

1. 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.

2. lack of accuracy or thoroughness.

   The many instances of carelessness in the book (with references, dates, etc.) detract from its value.

3. 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.

4. 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.

5. effortless or artless quality.

   She is a highly intelligent academic who nevertheless speaks with the simplicity and carelessness of a child.

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Other Word Forms

• overcarelessness noun

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

It’s not a smart thing to do, and it speaks to Robby’s current attitude of a certain amount of carelessness on his part.

From Los Angeles Times • Jan. 8, 2026

He said the files were accessed due to "carelessness", using passwords shared on messaging apps.

From Barron's • Dec. 17, 2025

“The degree of carelessness is remarkable,” said Nikos Passas, a professor of criminology at Northeastern University.

From The Wall Street Journal • Oct. 31, 2025

Their carelessness will be a concern for Slot, even if they have shown five times this season that they have what it takes to pull themselves out of trouble.

From BBC • Sep. 17, 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

Related Words

• inattention
• neglect
• negligence
• nonchalance
• sloppiness