From Middle English retarden, from Anglo-Norman - or Latin -, from Anglo-Norman retarder, from Latin retardāre, from re- + tardus ("slow").

• (British, America) IPA: /ɹɪˈtɑː(ɹ)d/
• (British, America) IPA: /ˈɹiːtɑː(ɹ)d/

retard (plural retards)

1. Retardation; delay.

   Synonyms: delay, hold-up, retardation

2. (music) A slowing down of the tempo; a ritardando.
3. (offensive, dated) A person with mental retardation.

   Synonyms: retarded, tard, imbecile, mental deficient, moron

   The retard in our class needs special help.

4. (informal, offensive) A person or being who is extremely stupid or slow to learn.

   Synonyms: Thesaurus:fool

• French: retard
• German: Verzögerung, Verspätung
• Russian: замедле́ние
• Spanish: perecear

• French: retardé
• Italian: ritardato mentale
• Russian: деби́л
• Spanish: retrasado, retrasada

• French: attardé
• Russian: то́рмоз
• Spanish: retrasado, retrasada

retard (retards, present participle retarding; simple past and past participle retarded)

1. (transitive) To keep delaying; to continue to hinder; to prevent from progressing.

   Synonyms: impede, hinder, hold up

   retard the march of an army

   retard the motion of a ship

2. (transitive) To put off; to postpone.

   to retard the attacks of old age

   to retard a rupture between nations

3. (transitive, obsolete) To be slow or dilatory to perform (something).
4. (intransitive) To decelerate; to slow down.
5. (intransitive, obsolete) To stay back.
   • 1650, Thomas Browne, Pseudodoxia Epidemica: […], 2nd edition, London: […] A[braham] Miller, for Edw[ard] Dod and Nath[aniel] Ekins, […], →OCLC ↗:

     Some years it [The River Nile] hath also retarded, and come far later than usually it was expected

• (keep delaying; continue to hinder) decelerate, hinder, slow, slow down; See also Thesaurus:hinder
• (postpone) postpone, put off; See also Thesaurus:procrastinate
• (decelerate) decelerate, slow, slow down, slow up
• (stay back) hang back, stay back; See also Thesaurus:tarry

• (antonym(s) of “keep delaying; continue to hinder”): accelerate, speed, speed up
• (antonym(s) of “postpone”):
• (antonym(s) of “stay back”): come forward

• German: verhindern
• Russian: заде́рживать

• German: verschieben, aufschieben
• Russian: откла́дывать

• German: zurückbleiben