retard

1 of 2

verb

re·​tard ri-ˈtärd 

retarded; retarding; retards

transitive verb

: to delay or impede the development or progress of : to slow up especially by preventing or hindering advance or accomplishment

chemicals to retard the spread of fire

intransitive verb

: to become delayed : to undergo retardation

retarder noun

retard

2 of 2

noun

re·​tard

plural retards

1

ri-ˈtärd  : a holding back or slowing down : retardation

2

ˈrē-ˌtärd  offensive : a person affected with intellectual disability

3

ˈrē-ˌtärd  informal + offensive : a foolish or stupid person

Synonyms

Verb

• brake
• decelerate
• slacken
• slow

Choose the Right Synonym for retard

delay, retard, slow, slacken, detain mean to cause to be late or behind in movement or progress.

delay implies a holding back, usually by interference, from completion or arrival.

bad weather delayed our arrival

retard suggests reduction of speed without actual stopping.

treatment that retards tumor growth

slow and slacken also imply a reduction of speed, slow often suggesting deliberate intention

she closed her eyes and slowed her breathing

, slacken an easing up or relaxing of power or effort.

on hot days runners slacken their pace

detain implies a holding back beyond a reasonable or appointed time.

unexpected business had detained her

Examples of retard in a Sentence

Verb

The chemical will retard the spread of fire.

The problems have retarded the progress of the program.

Recent Examples on the Web

Verb

Blockchain thus provides companies and banks a way to undo Basel II’s and Basel III’s retarding effect on trade finance while complying with their requirements. —Rebecca Liao, Foreign Affairs, 16 Aug. 2017

Turning the lithium oxide—the product of discharging the battery—back to lithium is difficult and only partially possible even when assisted by special catalysts: The oxide builds up and retards the process, limiting the number of charge-discharge cycles to a mere handful. —IEEE Spectrum, 31 Jan. 2011

Genesis Yes, the thing retarding recruitment below pre-2022 levels may be, at least in part, a military-wide health-records update that, much like MyChart in the civilian health-care world, tracks the medications of all service members. —Luther Ray Abel, National Review, 9 Feb. 2024

Traditional concern with fiscal deficits has focused on their impact in pushing up interest rates and retarding investment. —Lawrence H. Summers, Foreign Affairs, 15 Feb. 2016

It can be combatted by at least three means: by adding water injection, which Pontiac has avoided for a number of good reasons; by enriching the fuel-air mixture, which is unfortunately contrary to efficiency goals and therefore used sparingly; and by retarding ignition timing. —Don Sherman, Car and Driver, 1 May 2023

Word History

Etymology

Verb

Middle English, from Anglo-French or Latin; Anglo-French retarder, from Latin retardare, from re- + tardus slow

First Known Use

Verb

15th century, in the meaning defined at transitive sense

Noun

1781, in the meaning defined at sense 1

Kids Definition

retard

verb

re·​tard

ri-ˈtärd

: to slow up especially by preventing or checking progress : hinder

retarder noun

Medical Definition

retard

transitive verb

re·​tard ri-ˈtärd 

: to slow up especially by preventing or hindering advance or development

retard spoilage

retard hair loss