1. To diminish the velocity of motion; to hinder; to render more slow in progress; as, to retard the march of an army; to retard the motion of a ship. The resistance of air retards the velocity of a cannon ball. It is opposed to accelerate.
2. To delay; to put off; to render more late; as, to retard the attacks of old age; to retard a rupture between nations. My visit was retarded by business.
RET'ARD, v.i. To stay back. [Not in use.]