Summary: There are many things in life worth keeping unsullied or unsoiled. From our good name to our best dress shirt, it's preferable to keep things safe from both literal and figurative sullying or soiling. It would seem that "sully" and "soil" have a lot in common. So much so that a listener recently asked if they're related. In fact, they are. Sully comes from the French verb "souiller" which means to pollute or stain. That's the same meaning it had when it came into English in 1615, according to
