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

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

Synonyms of reinforcement

• support
• shore
• brace
• pillar
• mounting

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

In the first weeks of the war, the Syrian military sent reinforcements to the border with Lebanon, which officials said aimed to stop cross-border weapons smuggling or any spillover of the conflict. — ABC News, 28 June 2026

Some runs will be harder than others — no pain, no gain — but in my experience, positive reinforcement goes a long way. — Nicole Bennett, AJC.com, 26 June 2026

Piero Hincapie’s permanent move from Bayer Leverkusen after last season’s loan is the latest example of Arteta and Arsenal seeking further reinforcements when it was questioned whether they were needed. — Mark Carey, New York Times, 26 June 2026

This latest collapse, one where the bullpen allowed seven runs over three innings and Caleb Kilian allowed four in the ninth, serves as the latest example of the front office’s inability to reinforce a bullpen that needed reinforcements this winter. — Justice Delos Santos, Mercury News, 25 June 2026

Word History

First Known Use

1602, in the meaning defined at sense 1

Rhymes for reinforcement

• divorcement
• endorsement
• enforcement
• indorsement
• forcement

Kids 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