MOP, a bunch of cloth, rags or coarse yarn, fastened to a pole and serving as a broom or brush for swabbing up wet floors or other surfaces and for cleaning generally. The word is usually taken to be an adaptation of Lat. mappa, cloth, napkin, cf. " map." A particular application of the term in provincial English is to an annual hiring or statute-fair, a " mop-fair," at which domestic and agricultural servants out of places attended, carrying a broom, a mop or other implement indicative of their calling.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)