Unflustered means to remain calm and composed, even in challenging or difficult situations. Synonyms for unflustered include unperturbed, composed, level-headed, calm, cool, collected, serene, tranquil, and unruffled. These words describe a person who doesn't allow external pressures or emotions to disturb their peace of mind. Being unflustered is a quality that denotes a person's poise and maturity. People who exhibit such qualities are highly valued in leadership positions. Unflustered is a perfect word to describe a person who remains cool and calm under pressure, who is able to think and act rationally and whose demeanor remains the same even in difficult circumstances.