<p><strong>Noun</strong></p><ul><li>A discoloration produced by foreign matter having penetrated into or chemically reacted with a material; a spot not easily removed.</li><li>A natural spot or patch of color different from that of the basic color, as on the body of an animal.</li><li>A cause of reproach; stigma; blemish: a stain on one's reputation.</li><li>Coloration produced by a dye that penetrates a substance, as wood.</li><li>A dye made into a solution for coloring woods, textiles, etc.</li><li>A reagent or dye used in treating a specimen for microscopic examination.</li></ul><p><strong>Verb</strong></p><ul><li>To discolor with spots or streaks of foreign matter.</li><li>To bring reproach or dishonor upon; blemish.</li><li>To sully with guilt or infamy; corrupt.</li><li>To color or dye (wood, cloth, etc.) by any of various processes that change or react with the substance chemically.</li><li>To produce a stain.</li><li>To become stained; take a stain: This fabric stains easily.</li></ul>