retard

v. 1 make slow or late. 2 delay the progress or accomplishment of.  retardant adj. & n. Retardation n. [latin tardus slow]

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.