professor

1. (US, Philippines, informal) A teacher or faculty member at a college or university regardless of formal rank.PhilippinesUSinformal

2. (archaic) One who professes something, such as a religious doctrine.Examples: "As for Religion, I have not said, much lesse meant irreverently of it, or of the Professors thereof."; "This period in which Abraham the Jew lived was one in which Magic was almost universally believed in, and in which its Professors were held in honour;"archaic

3. (obsolete) A practitioner, one who (publicly) practises or teaches an art or skill.Examples: "Two young men of familiar acquaintance … were one euening at a common Inne of this town (as I haue heard) where the one of them shewed his skill on the Virginals, to the no little contentement of the hearers. Nowe as diuers guests of the house came into the room to listen, so among the rest entered an artificiall Conny-catcher, who as occasion serued, in the time of ceissing betweene the seueral toyes and fancies hee plaid: very much commended his cunning, quicke hand, and such qualities praiseworthy in such a professour."obsolete

4. (US, slang) A pianist in a saloon, brothel, etc.Examples: "You could hear [...] pianos under the hands of whorehouse professors sounding like they came with keys between the keys."USslang