Delayed; delayed in development, hindered; impeded. / (psychology, now offensive, dated) Having mental retardation; mentally deficient or underdeveloped.

simple past tense and past participle of retard

(physics) The difference in phase shift between two characteristic polarizations of light upon reflection from an interface. Retardance can be reported in the Abelès or Mueller conventions. The retardance phase shift angle is often specified in degrees.

(acoustics) The distance by which one wave is behind another. / (music) The act of diminishing the rate of speed. / (telegraphy) A decrease in the speed of telegraph signalling.

plural of retardation

plural of retard

Third-person singular simple present indicative form of retard

present participle of retard

A slowing or hindrance.

(often in combination) Serving to impede (slow down) the action of something