IPA: /rɪˈtɑːrdɪd/
KK: /rɪˈtɑrdɪd/
Describing someone or something that is slower than usual in development or progress, often used in a negative or offensive way to refer to limited intellectual or emotional growth.
The project was retarded due to unforeseen circumstances, causing delays in its completion.
Retarded is formed from "re-" (meaning back or again) and "tardare" (meaning to delay or make late). The word originally referred to something that is delayed or slowed down.
Think of something being 'held back' ('re-') and 'delayed' ('tardare') — that's why retarded means delayed or slowed down.