stain

noun

1
an act that brings discredit to the person who does it
he made a huge blot on his copybook
2
a soiled or discolored appearance
the wine left a dark stain
3
a symbol of disgrace or infamy
And the Lord set a mark upon Cain"--Genesis
4
the state of being covered with unclean things
5
(microscopy) a dye or other coloring material that is used in microscopy to make structures visible

1
color for microscopic study
The laboratory worker dyed the specimen
2
color with a liquid dye or tint
Stain this table a beautiful walnut color
people knew how to stain glass a beautiful blue in the middle ages
3
produce or leave stains
Red wine stains the table cloth
4
make dirty or spotty, as by exposure to air; also used metaphorically
The silver was tarnished by the long exposure to the air
Her reputation was sullied after the affair with a married man

Also useful for “stain”:Wordle Solver— Five letters — perfect Wordle material