To discolor, as by the application of some foreign matter; make foul; spot: as, to stain the hand with dye, or with tobacco-juice; to stain the clothes.To soil or sully with guilt or infamy; tarnish; bring reproach on; corrupt; deprave: as, to stain the character; stained with guilt.To deface; disfigure; impair, as shape, beauty, or excellence.To color by a process other than painting or coating or covering the surface.To print colors upon (especially upon paper-hangings).To darken; dim; obscure.Hence To eclipse; excel.To cause a stain or discoloration.To take stains; become stained, soiled, or sullied; grow dim; be obscured.n. A spot; a discoloration, especially a discoloration produced by contact with foreign matter by external causes or influences: as, mildew-stains.n. A blot; a blemish; a cause of reproach or disgrace: as, a stain on one's character.n. In entomology, a well-defined spot of color which appears to be semi-transparent, so that it merely modifies the ground-color: it may be produced by very fine dots, as on a butterfly's wing.n. Taint; tarnish; evil or corrupting effect: as, the stain of sin.n. Slight trace; tinge; tincture.n. Coloring matter; a liquid used to color wood, ivory, etc., by absorption.n. Specifically, a solution of a dye used in microscopical work to render more readily visible various structures, and for purposes of differentiation.