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

His elite resume made his June retirement a surprise to many, and his decision to unretire just before the playoff push feel like an important, timely reinforcement. —Rowan Fisher-Shotton, MSNBC Newsweek, 29 Nov. 2025

Chatbots trained with reinforcement learning have mastered the art of intermittent delight. —Kaif Shaikh, Interesting Engineering, 28 Nov. 2025

With injuries striking the roster the last couple of weeks, the Rams (9-2) are looking to add some reinforcements this week ahead of their game against the Carolina Panthers (6-6). —Adam Grosbard, Oc Register, 27 Nov. 2025

Getting reinforcements back at just the right time could prove key for Miami over this final stretch. —Jordan McPherson, Miami Herald, 21 Nov. 2025

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