Available Definitions:
1) v. t. - To keep delaying; to continue to hinder; to prevent from progress; to render more slow in progress; to impede; to hinder; as, to retard the march of an army; to retard the motion of a ship; -- opposed to accelerate.
2) v. t. - To put off; to postpone; as, to retard the attacks of old age; to retard a rupture between nations.
3) v. i. - To stay back.
4) n. - Retardation; delay.