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deter

American  
[dih-tur] / dɪˈtɜr /

verb (used with object)

deters, present (3rd person singular) deterred, past participle, past deterring present participle
  1. to discourage or restrain from acting or proceeding.

    The large dog deterred trespassers.

  2. to prevent; check; arrest.

    timber treated with creosote to deter rot.

  3. to repel.

    Strongly scented marigolds planted among the melons are supposed to deter beetles.


deter British  
/ dɪˈtɜː /

verb

  1. (tr) to discourage (from acting) or prevent (from occurring), usually by instilling fear, doubt, or anxiety

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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Etymology

Origin of deter

First recorded in 1570–80; from Latin dēterrēre “to discourage, put off, frighten,” equivalent to dē-, prefix and preposition + terrēre “to frighten, scare”; see de-

Explanation

Deter means to discourage, or literally “to frighten away.” Halloween decorations that are too scary might deter trick-or-treaters, and the risk of being expelled deters kids from cheating in school. Deter comes from the Latin de meaning "away" and terrere meaning "frighten." Something that deters isn’t always scary, though: citronella plants deter mosquitoes, and fines deter people from littering. Teddy Roosevelt's foreign policy dictum "speak softly and carry a big stick" was meant to deter other countries from attacking the United States.

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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.

With the population of college-goers shrinking in coming years, higher-education institutions are fighting over a smaller pie—and supplemental essays can deter applicants.

From The Wall Street Journal • Jul. 10, 2026

"This very real debt would also deter potential learners from entering higher education in the first place, while making it harder for people to return to education later in life."

From BBC • Jul. 8, 2026

But the searing temperatures have done little to deter President Donald Trump, who has gone to great lengths to ensure the event becomes, in large part, a celebration of himself.

From Barron's • Jul. 4, 2026

The eminently sane Mr. Smith understands the need to shorten such timelines to better deter China.

From The Wall Street Journal • Jul. 1, 2026

Perhaps the simple fact of seeing her there at work would deter the women who hoped to drive her away.

From "Gathering Blue" by Lois Lowry

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