To mop means to clean a floor using a tool called a mop, which has a long handle attached to absorbent strips of cloth or sponge. When you mop, you dip the mop head in soapy water, wring it out, and then sweep it across the floor to pick up dirt, spills, and grime. After a big party or a kitchen accident, someone needs to mop up the mess.

The word can also mean wiping or soaking up liquid more generally. A basketball player might mop sweat from their forehead with a towel during a timeout. When a cleanup crew finishes dealing with the last details of a problem, people sometimes say they're mopping up loose ends.

As a noun, a mop is the cleaning tool itself. Traditional mops have stringy cotton strips, while newer ones might use sponges or microfiber cloths. Some people also use mop to describe very messy, tangled hair, like saying someone just woke up with a mop of curls sticking out in every direction.