Top definition
A name given by 1970s UK washing powder manufacturers for stains that won't wash out. A polite word for shit or bodily fluids of some sort on underwear.
"Has your washing got understains you can't remove"? "Use new Daz powder to remove them fast"!
by prof_evil April 23, 2011
Get the mug
Get a Understains mug for your Facebook friend Rihanna.