Real Dictionary

mop
countable noun: A mop is a piece of equipment for washing floors. It consists of a sponge or many pieces of string attached to a long handle.
verb: If you mop a surface such as a floor, you clean it with a mop.
verb: If you mop sweat from your forehead or mop your forehead, you wipe it with a piece of cloth.

mop in American English 1
a bundle of loose rags or yarns, a sponge, etc. fastened to the end of a stick, as for washing or wiping floors
to wash, rub, wipe, or remove with or as with a mop
intransitive verb: to clean or wipe with or as if with a mop
noun: a bundle of coarse yarn, a sponge, or other absorbent material, fastened at the end of a stick or handle for washing floors, dishes, etc
transitive verb: to rub, wipe, clean, or remove with a mop

mop in American English 2
grimace
intransitive verb: to make a disappointed or unhappy face; grimace
noun: a wry face; grimace

mop in British English 1
noun: an implement with a wooden handle and a head made of twists of cotton or a piece of synthetic sponge, used for polishing or washing floors, or washing dishes
verb: to clean or soak up with or as if with a mop

mop in British English 2
noun: such a face or expression
verb: to make a grimace or sad expression (esp in the phrase mop and mow)

mop in British English 3
noun: (formerly, in various parts of England) an annual fair at which servants were hired