re·in·force | \ˌrē-ən-ˈfȯrs \
variants: or less commonly

Definition of reinforce 

transitive verb

1 : to strengthen by additional assistance, material, or support : make stronger or more pronounced reinforce levees reinforce the elbows of a jacket reinforce ideas

2 : to strengthen or increase by fresh additions reinforce our troops were reinforcing their pitching staff

3 : to stimulate (a subject, such as an experimental animal) by reinforcement (see reinforcement sense 3) also : to encourage (a response) by reinforcement

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Other Words from reinforce

reinforceable \ˌrē-ən-ˈfȯr-sə-bəl \ adjective

Examples of reinforce in a Sentence

The captain sent out another squad to reinforce the troops. Our camp is reinforced with supplies flown in by helicopter. The levees will need to be reinforced. The bad weather forecast only reinforces our decision to leave early tomorrow. Some critics say that the movie reinforces negative stereotypes about the military. We do our best to reinforce good conduct in the classroom.
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Recent Examples on the Web

Southworth's commitment to creating mobile apps and other software that help others was reinforced this week. Jessica Guynn, USA TODAY, "This teen, who attempted suicide seven times, builds apps that saved her own life and others," 9 June 2018 The Netflix show 13 Reasons Why, for example, positions suicide as a conduit for revenge, arguably reinforcing the idea that death by suicide is the only way for those struggling with mental illness to be seen, heard, and appreciated. Danielle Campoamor, Marie Claire, "​It's Time to Talk About the Media's Role in Rising Suicide Rates​," 8 June 2018 Offering a test for Down syndrome alongside tests for conditions like HIV reinforces the idea that this syndrome is hazardous. Chris Kaposy, STAT, "Children with Down syndrome live good lives. Prenatal testing shouldn’t nudge parents toward pregnancy termination," 18 May 2018 One answer is that such a narrative reinforces white Americans’ faith in their nation’s capacity to assimilate immigrants, and preserve a common set of cultural values and symbols. Eric Levitz, Daily Intelligencer, "America Will Only Remain ‘Majority White’ If Blacks Remain An Underclass," 3 May 2018 And those doubts have been reinforced in recent days by intelligence showing that North Korea, far from dismantling its weapons facilities, has been expanding them and taking steps to conceal the efforts from the United States. New York Times, "North Korea Criticizes ‘Gangster-Like’ U.S. Attitude After Talks With Mike Pompeo," 7 July 2018 And those doubts have been reinforced in recent days by intelligence showing that North Korea, far from dismantling its weapons facilities, has been expanding them and taking steps to conceal the efforts. Gardiner Harris,, "North Korea calls US talks ‘deeply regrettable’," 7 July 2018 The front door to the building was boarded-up, reinforced by padlocks and covered in graffiti. Billboard, "Eerie Waves: Memories of an Abandoned Radio Home, From Dido to Whitesnake's David Coverdale (& the Incredible Hulk)," 6 July 2018 But that geographical advantage was swiftly reinforced by the integration of Canadian and U.S. defense. Danielle Bochove,, "Trump’s Trade War Looms Over a Canadian Town Built to Supply America," 28 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'reinforce.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of reinforce

15th century, in the meaning defined at transitive sense 1

History and Etymology for reinforce

re- + inforce, alteration of enforce

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Statistics for reinforce

Last Updated

20 Oct 2018

Look-up Popularity

Time Traveler for reinforce

The first known use of reinforce was in the 15th century

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More Definitions for reinforce



English Language Learners Definition of reinforce

: to strengthen (a group of people) with new supplies or more people

: to strengthen (something, such as clothing or a building) by adding more material for support

: to encourage or give support to (an idea, behavior, feeling, etc.)


re·in·force | \ˌrē-ən-ˈfȯrs\
reinforced; reinforcing

Kids Definition of reinforce

1 : to strengthen with new supplies or more people Another squad reinforced the troops.

2 : to strengthen by adding more material for support The wall needs to be reinforced.


transitive verb
re·in·force | \ˌrē-ən-ˈfō(ə)rs, -ˈfȯ(ə)rs \
reinforced; reinforcing

Medical Definition of reinforce 

1 : to strengthen by additional material or support : make stronger reinforced with vitamins

2 : to stimulate (as an experimental animal or a student) by reinforcement also : to encourage (a response) by reinforcement

Other Words from reinforce

reinforceable \-ə-bəl \ adjective

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Comments on reinforce

What made you want to look up reinforce? Please tell us where you read or heard it (including the quote, if possible).


to reject or criticize sharply

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