stain

noun

1. A discolored spot or area caused by spillage or other contact with certain fluids or substances.
2. A blemish on one's character or reputation.
3. A substance used to soak into a surface and colour it.

   “The wood will darken whether it is stained or not—the main function of a stain is to enhance the wood's natural color and emphasize its grain.”

4. A reagent or dye used to stain microscope specimens so as to make some structures visible.
5. One of a number of non-standard tinctures used chiefly in post-medieval heraldry, especially tenné, murrey, or sanguine.

verb

1. (transitive)To discolor, as by spilling or other contact with a fluid or substance.

   “to stain the hand with dye”

   “armour stained with blood”

2. To taint or tarnish someone's character or reputation

   “of Honour void, Of Innocence, of Faith, of Puritie, Our wonted Ornaments now soild and staind”

3. To coat a surface with a stain

   “to stain wood with acids, coloured washes, paint rubbed in, etc.”

   “the stained glass used for church windows”

4. (intransitive)To become stained; to take a stain.
5. (transitive)To treat (a microscopic specimen) with a dye, especially one that dyes specific features
6. To cause to seem inferior or soiled by comparison.

   “She stains the ripest virgins of her age.”

   “that did all other beasts in beauty stain”