reinforcement
noun
re·in·force·ment
ˌrē-ən-ˈfȯrs-mənt 
1
: the action of strengthening or encouraging something : the state of being reinforced
2
: something that strengthens or encourages something: such as
a
: an addition of troops, supplies, etc., that augments the strength of an army or other military force
—usually plural
About 8 a.m. Soviet tanks and armored personnel carriers containing reinforcements approached the gorge from the right flank.—
John Barron
John Barron
b
: something designed to provide additional strength (as in a weak area)
a bridge in need of steel reinforcements
c
: a response to someone's behavior that is intended to make that person more likely to behave that way again
positive/negative reinforcement
3
psychology
: the action of causing a subject to learn to give or to increase the frequency of a desired response that in classical conditioning involves the repeated presentation of an unconditioned stimulus (such as the sight of food) paired with a conditioned stimulus (such as the sound of a bell) and that in operant conditioning involves the use of a reward following a correct response or a punishment following an incorrect response
also
: the reward, punishment, or unconditioned stimulus used in reinforcement
Examples of reinforcement in a Sentence
“We're outnumbered! Call for reinforcements!”
We need to prevent enemy reinforcements from reaching the front line.
The bridge is in need of reinforcement.
You should encourage good behavior with positive reinforcement.
Recent Examples on the Web
Efforts by Russian units to dig in within the city’s northern districts have failed, leaving those forces unable to withdraw or receive reinforcements, Ukrainian officials said.
—Greg Wehner, FOXNews.com, 26 Dec. 2025
Additional reinforcements With tight end Nate Adkins’ knee banged up again, the Broncos signed 41-year-old veteran Marcedes Lewis back to their active roster on Christmas Day.
—Luca Evans, Denver Post, 25 Dec. 2025
Then, losses suffered at another of World War II’s bloodiest campaigns, the Normandy invasion that commenced with D-Day on June 6, 1944, led to a need for reinforcements like Buford.
—Graham Womack, Sacbee.com, 25 Dec. 2025
Rex Specs includes training tips, which involve positive reinforcement (with treats for Hatchet) and fitting the goggles without lens first.
—Natalie Krebs, Outdoor Life, 24 Dec. 2025
See All Example Sentences for reinforcement
Examples are automatically compiled from online sources to
show current usage.
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Greg Wehner, FOXNews.com, 26 Dec. 2025
Additional reinforcements With tight end Nate Adkins’ knee banged up again, the Broncos signed 41-year-old veteran Marcedes Lewis back to their active roster on Christmas Day.
—Luca Evans, Denver Post, 25 Dec. 2025
Then, losses suffered at another of World War II’s bloodiest campaigns, the Normandy invasion that commenced with D-Day on June 6, 1944, led to a need for reinforcements like Buford.
—Graham Womack, Sacbee.com, 25 Dec. 2025
Rex Specs includes training tips, which involve positive reinforcement (with treats for Hatchet) and fitting the goggles without lens first.
—Natalie Krebs, Outdoor Life, 24 Dec. 2025
See All Example Sentences for reinforcement
Cite this Entry
“Reinforcement.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/reinforcement. Accessed 1 Jan. 2026.
Copy CitationKids Definition
reinforcement
noun
re·in·force·ment
ˌrē-ən-ˈfōr-smənt
-ˈfȯr-
1
: the action of reinforcing : the state of being reinforced
2
: something that reinforces
Medical Definition
reinforcement
noun
re·in·force·ment
ˌrē-ən-ˈfōr-smənt, -ˈfȯr-
: the action of causing a subject (as a student or an experimental animal) to learn to give or to increase the frequency of a desired response that in classical conditioning involves the repeated presentation of an unconditioned stimulus (as the sight of food) paired with a conditioned stimulus (as the sound of a bell) and that in operant conditioning involves the use of a reward following a correct response or a punishment following an incorrect response
also
: the reward, punishment, or unconditioned stimulus used in reinforcement compare recruitment sense 1
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