reinforce

UK: /ˌriːɪnˈfɔː^rs/ US: /ˌriɪnˈfɔrs/ ,(rē′in fôrs′, -fōrs′)

Inflections of 'reinforce' (v): (⇒ conjugate)

reinforces

v 3rd person singular

reinforcing

v pres p

reinforced

v past

reinforced

v past p

WordReference Random House Learner's Dictionary of American English © 2026

re•in•force or re•en•force /ˌriɪnˈfɔrs/   v. [~ + object] , -forced, -forc•ing. 

1. to strengthen with some added piece, support, or material:
   to reinforce a wall.
2. to make more forceful or effective;
   strengthen;
   support:
   to reinforce the law.
3. to strengthen (a military force) with additional soldiers, ships, aircraft, etc.
4. Psychology Psychol. to strengthen the likelihood of (a desired way of behaving) by giving or withholding a reward.

See -fort-.

WordReference Random House Unabridged Dictionary of American English © 2026

re•in•force  (rē′in fôrs′, -fōrs′), v., -forced, -forc•ing, n. 
v.t. 

1. to strengthen with some added piece, support, or material:
   to reinforce a wall.
2. to strengthen (a military force) with additional personnel, ships, or aircraft:
   to reinforce a garrison.
3. to strengthen;
   make more forcible or effective:
   to reinforce efforts.
4. to augment;
   increase:
   to reinforce a supply.
5. Psychology to strengthen the probability of (a response to a given stimulus) by giving or withholding a reward.

n. 

6. something that reinforces.
7. a metal band on the rear part of the bore of a gun, where the explosion occurs.

Also, reenforce, re-enforce. 

• re- + inforce, alteration of enforce 1590–1600

re′in•forc′er, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

reinforce / ˌriːɪnˈfɔːs/ verb (transitive)

1. to give added strength or support to
2. to give added emphasis to; stress, support, or increase: his rudeness reinforced my determination
3. to give added support to (a military force) by providing more men, supplies, etc

Etymology: 17th Century: from obsolete renforce, from French renforcer; see re- + inforce enforce

ˌreinˈforcement noun