(archaic) Easily fooled, gullible.

A large cup for beverages, usually having a handle and used without a saucer. / (slang, often derogatory) The face. / (slang, derogatory) A gullible or easily-cheated person.

(transitive, obsolete, UK) To strike in the face. / (transitive) To assault for the purpose of robbery.

(slang, African-American Vernacular) Motherfucker (usually in similes, e.g. "like a mug" or "as a mug")

A quick violent robbery of a person, usually in a public place.

present participle of mug

plural of mug

Third-person singular simple present indicative form of mug

As much as a mug will contain.

plural of mugful