professor

Etymology

From Anglo-Norman proffessur, from Latin professor (“declarer, person who claims knowledge”), from the past participle stem of profiteor (“profess”).

noun

1. The most senior rank for an academic at a university or similar institution, informally also known as "full professor."
   Professor is what you become after teaching for twenty to thirty years. 2014-11-22, Michel Clasquin-Johnson, “What is the difference between a research professor and a professor”, in Quora
2. (US, informal) A teacher or faculty member at a college or university regardless of formal rank.
3. (archaic) One who professes something, such as a religious doctrine.
   As for Religion, I have not said, much lesse meant irreverently of it, or of the Professors thereof. 1660, William Petty, Reflections upon some Persons and Things in Ireland, p. 170/1
   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; 1897, Samuel Liddell MacGregor Mathers (transl.) The Book of the Sacred Magic of Abramelin the Mage, Introduction, p. v
4. (US, slang) A pianist in a saloon, brothel, etc.
   You could hear … pianos under the hands of whorehouse professors sounding like they came with keys between the keys. 2006, Thomas Pynchon, Against the Day, Vintage, published 2007, page 415
5. The puppeteer who performs a Punch and Judy show; a Punchman.