"Keep countenance" is an idiomatic expression that means to maintain one's composure or to keep a serious or calm appearance. Synonyms for this phrase include "maintain one's dignity," "keep one's self-control," "remain composed," "stay unruffled," and "keep a straight face." These words are often used in situations where one needs to maintain a professional or serious demeanor, especially in difficult or unexpected circumstances. Keeping countenance is an essential skill to develop in both personal and professional lives, as it helps to portray a sense of confidence and control, especially in difficult or challenging situations where staying collected is necessary.