Yes, stain is a Scrabble word!

Verb

1. Color with a liquid dye or tint

2. Produce or leave stains

3. Make dirty or spotty, as by exposure to air; also used metaphorically

4. Color for microscopic study

Noun

1. A soiled or discolored appearance

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

3. The state of being covered with unclean things

4. A symbol of disgrace or infamy

5. An act that brings discredit to the person who does it