1) At ease 2) Calm 3) Collected 4) Composed 5) Cool 6) Cool as a cucumber 7) Even 8) Imperturbable 9) Placid 10) Sedate 11) Serene 12) Smooth 13) Stoic 14) Tranquil 15) Unflurried 16) Unflustered 17) Unperturbed 1) Calm 2) Composed 3) Not ruffled or agitated 4) Smooth 5) Steady 6) Tranquil, unperturbed 7) Unflurried 8) Unflustered 9) Unperturbed 
• (a.) Not ruffled or agitated; smooth; calm; tranquil; quiet.
HMS Unruffled was a British Ursula Class submarine of 540 tons displacement launched in the early 1940s. She was armed with one small gun and six 21-inch torpedo tubes in the bow. She had a top speed of 11.25 knots surfaced and 10 knots submerged and carried a complement of 27.
calm; not emotionally upset or agitated; steady; unflustered: He became all excited, but she remained unruffled. · not ruffled, as a garment; smooth.