Retard
noun
Retardation; delay.
A slowing down of the tempo; a ritardando.
A person with mental retardation.
“The retard in our class needs special help.”
Synonyms: idiot, imbecile, learning difficulties, mental deficient, moron, retarded, tard, delay
verb
To keep delaying; to continue to hinder; to prevent from progress
“retard the march of an army”
To put off; to postpone.
“to retard a rupture between nations”
To be slow or dilatory to perform (something).
Synonyms: decelerate, slow, slow down, slow up, decelerate, hinder, slow, slow down