stain definition

1. a soiled or discolored appearance
• examples: the wine left a dark stain
2. (microscopy) a dye or other coloring material that is used in microscopy to make structures visible
3. color with a liquid dye or tint
• examples: Stain this table a beautiful walnut color
• examples: people knew how to stain glass a beautiful blue in the middle ages
4. produce or leave stains
• examples: Red wine stains the table cloth
5. color for microscopic study
• examples: The laboratory worker dyed the specimen