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

Government forces brought in reinforcements into Suqaylabiyah, calming the violence. —ABC News, 28 Mar. 2026

Eight years and 400,000 pounds of steel reinforcement later, Michter's Fort Nelson opened in 2019. —Adam Sachs, Condé Nast Traveler, 28 Mar. 2026

By then, the element of surprise is gone, the force may face enemy reinforcements, and the operators' exhaustion increases the likelihood of mistakes. —Sheena Samu, CBS News, 27 Mar. 2026

Mounting destruction, death toll Satellite imagery reviewed by NBC News appeared to show the reinforcement in the lead-up to or during the current war of five Israeli military bases that were set up during previous incursions into southern Lebanon. —Chantal Da Silva, NBC news, 27 Mar. 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