(MEEN)
(n.) 1. Manner or bearing, especially as it expresses one's inner personality or state of mind
2. Appearance or aspect

"Mien" comes from Middle English "demeine," meaning "behavior." The Middle English term, in turn, derives from Old French "demener," meaning "to behave."

A related word, "demean," is sometimes used with the sense of "to conduct oneself in a proper manner." (Hence also our word "demeanor.") But note: None of these related words are relatives of the other kind of "demean," as in "to debase" or "to humble." The literal sense of that word is "to make 'mean'"--that is, "to make small or insignificant."

"The nice, calm, tempered and reasonable Dick Cheney who won rave reviews for his performance during Thursday night's vice-presidential debate stepped aside Friday morning, returning to his rather nasty attack-dog mien."--Jake Tapper in Salon magazine.