staining

(noun) (histology) the use of a dye to color specimens for microscopic study.

(noun) the act of spotting or staining something. Synonyms: spotting, maculation.

(verb) color with a liquid dye or tint. Synonyms: stain. Examples: "Stain this table a beautiful walnut color." "People knew how to stain glass a beautiful blue in the middle ages."

(verb) produce or leave stains. Synonyms: stain. Example: "Red wine stains the table cloth."

(verb) make dirty or spotty, as by exposure to air; also used metaphorically. Synonyms: tarnish, stain, maculate, sully, defile. Examples: "The silver was tarnished by the long exposure to the air." "Her reputation was sullied after the affair with a married man."

(verb) color for microscopic study. Synonyms: stain. Example: "The laboratory worker dyed the specimen."