demeanor
n. uncountablen. the way you look and act, which shows people your personality or how you are feeling.
n. outward behaviour or bearing; the way in which a person conducts themselves. Often reflects an underlying emotional state or social status.
He maintained a calm demeanor even during the difficult meeting.
The doctor's professional demeanor immediately put the nervous patient at ease.
Despite the intense scrutiny of the courtroom, the witness maintained a stoic demeanor that made it difficult for the jury to gauge her true reaction to the evidence.
From Middle English demenure, from the verb Middle English demenen, demeinen (“to handle, manage”), from Old French demener (“to guide, conduct”), from de- + mener (“to conduct, lead”), from Latin *mināre (“to drive”) and minor (“to project or jut forth”).
Usually uncountable when referring to a person's general manner; occasionally used with an adjective to describe a specific style of behavior.