What is the meaning of staining?

noun

• Histology) the use of a dye to color specimens for microscopic study. (
• The act of spotting or staining something.
  • synonyms: spotting, maculation

verb

• Color with a liquid dye or tint.
  • usage: "Stain this table a beautiful walnut color"; "people knew how to stain glass a beautiful blue in the middle ages"
  • synonyms: stain
• Produce or leave stains.
  • usage: "Red wine stains the table cloth"
  • synonyms: stain
• Make dirty or spotty, as by exposure to air; also used metaphorically.
  • usage: "The silver was tarnished by the long exposure to the air"; "Her reputation was sullied after the affair with a married man"
  • synonyms: tarnish, stain, maculate, sully, defile
• Color for microscopic study.
  • usage: "The laboratory worker dyed the specimen"
  • synonyms: stain