stagnant vaginal secretions from a grandmoter
"Granny left some mop water when she got up from her chair"
a female dirtier than your average street walker, the town whore or your ex-boyfriends cheat; a more fragrant criticism than the use of the word "cunt"
Mr. Post declared his lady friend to be nothing finer or classier than mopwater.
Homemade iced tea; Another way of telling someone you have iced tea that you made, the term comes from the fact that homemade iced tea looks like mop water and the joke that a waiter/waitress that does not like a customer will bring them their iced tea with dirty water usually from a bucket that was used to clean the floor with.
My friend asked me what I had to drink and I told him that I just made mop water an hour ago if he wanted that.