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

What's important here is, even more so than Crackdown before it, Sunset Overdrive's traversal for such collectibles is reinforced with a mix of enjoyable, controllable speed and constant, reaffirming rewards. Sam Machkovech, Ars Technica, "Sunset Overdrive review: Ride the rails to kaboom-town (finally on PCs, too)," 17 Nov. 2018 An election conducted as a referendum on Mr. Trump thus had the effect of reinforcing the ranks of Trump loyalists. Allen C. Guelzo, WSJ, "The Blue Wave Breaks Gently," 9 Nov. 2018 Elizabeth Gillespie McRae’s groundbreaking book, Mother of Massive Resistance: White Women and the Politics of White Supremacy, offers a robust history of how white women reinforce white supremacy. Treva B. Lindsey, Vox, "The betrayal of white women voters: in pivotal state races, they still backed the GOP," 9 Nov. 2018 This is common among many disabled people, so the team at Nike focused on reinforcing that area to allow for more cushioning and durability while also helping with stability. Allen Kim, CNN, "Air Justins? Runner with cerebral palsy inspires Nike line," 16 May 2018 What purpose is there to reinforcing societal standards of the past that depress society today? Junot Díaz, The New Yorker, "The Mail," 7 May 2018 Each encounter reinforced the lack of humanity with which our male peers viewed women, our bodies, and our autonomy. Caroline Reilly, Teen Vogue, "Brett Kavanaugh Could Have Been a Virgin and Still Sexually Assaulted Dr. Ford," 30 Sep. 2018 Overall, this significant jump in orbital launches reinforces the seriousness of Chinese activities in space. Eric Berger, Ars Technica, "Rocket Report: Exos flies, China sets launch record, new Falcon Heavy data," 31 Aug. 2018 Worrying about Hollywood’s readiness just reinforces its power. Brooke Hauser, Marie Claire, "Constance Wu Is Taking It Upon Herself to Diversify Hollywood," 24 Aug. 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

1 Dec 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 enclose within walls

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