retard

v. t. [ imp. & p. p. Retarded; p. pr. & vb. n. Retarding. ] [ L. retardare, retardatum; pref. re- re- + tardare to make slow, to delay, fr. tardus slow: cf. F. retarder. See Tardy. ] 1. 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. [ 1913 Webster ]

2. To put off; to postpone; as, to retard the attacks of old age; to retard a rupture between nations. [ 1913 Webster ]

Syn. -- To impede; hinder; obstruct; detain; delay; procrastinate; postpone; defer. [ 1913 Webster ]

v. i. To stay back. [ Obs. ] Sir. T. Browne. [ 1913 Webster ]

n. [ L. retardatio: cf. F. retardation. ] 1. The act of retarding; hindrance; the act of delaying; as, the retardation of the motion of a ship; -- opposed to acceleration. [ 1913 Webster ]

The retardations of our fluent motion. De Quinsey. [ 1913 Webster ]

2. That which retards; an obstacle; an obstruction. [ 1913 Webster ]

Hills, sloughs, and other terrestrial retardations. Sir W. Scott. [ 1913 Webster ]

3. (Mus.) The keeping back of an approaching consonant chord by prolonging one or more tones of a previous chord into the intermediate chord which follows; -- differing from suspension by resolving upwards instead of downwards. [ 1913 Webster ]

4. The extent to which anything is retarded; the amount of retarding or delay. [ 1913 Webster ]

Retardation of the tide. (a) The lunitidal interval, or the hour angle of the moon at the time of high tide any port; the interval between the transit of the moon and the time of high tide next following. (b) The age of the tide; the retard of the tide. See under Retard, n. [ 1913 Webster ]

a. [ Cf. F. retardatif. ] Tending, or serving, to retard. [ 1913 Webster ]

n. having a limited or below normal mental ability; same as
mentally retarded; -- used especially in relation to performance in academic tasks. [ PJC ]

n. 1. One who, or that which, retards. [ 1913 Webster ]

2. (Steam Boiler) Any of various devices, as a helix of flat metal strip, introduced into a boiler tube to increase the heating effect of the fire. [ Webster 1913 Suppl. ]

3. (Photog.) A substance, as potassium bromide, added to a developer to retard its action. [ Webster 1913 Suppl. ]