Mop, v. t. [imp. & p. p. Mopped; p. pr. & vb. n. Mopping.]
To rub or wipe with a mop, or as with a mop; as, to mop a floor; to mop one's face with a handkerchief.
3 other Webster entries under this spelling
Mop, n.
A made-up face; a grimace. "What mops and mowes it makes!" Beau. & Fl.
Mop, v. i.
To make a wry mouth. [Obs.] Shak.
Mop, n.
1. An implement for washing floors, or the like, made of a piece of cloth, or a collection of thrums, or coarse yarn, fastened to a handle.
2. A fair where servants are hired. [Prov. Eng.]
3. The young of any animal; also, a young girl; a moppet. [Prov. Eng.] Halliwell. Mop head. (a) The end of a mop, to which the thrums or rags are fastened. (b) A clamp for holding the thrums or rags of a mop. [U.S.]
Shades of meaning
Fernald has no entry of its own for mop; he lists it under cleanse.
He lists it without comment; the entries above explain its neighbors.