carelessness

n.

The quality or state of being careless; heedlessness; negligence; inattention.

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noun

A careless, often reckless disregard for consequences: abandon, heedlessness, thoughtlessness. See careful/careless.

IN BRIEF: Failure to act properly.

My mom told me that because of my carelessness, I spilled the milk.

Note: click on a word meaning below to see its connections and related words.

The noun has 2 meanings:

Meaning #1: the quality of not being careful or taking pains
  Antonym: carefulness (meaning #2)

Meaning #2: failure to act with the prudence that a reasonable person would exercise under the same circumstances
  Synonyms: negligence, neglect, nonperformance

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