Stain

a soiled or discolored appearance

(microscopy) a dye or other coloring material that is used in microscopy to make structures visible

the state of being covered with unclean things

a symbol of disgrace or infamy

an act that brings discredit to the person who does it

color with a liquid dye or tint

produce or leave stains

make dirty or spotty, as by exposure to air

color for microscopic study