composed -
serenely self-possessed and free from agitation especially in times of stress; "the performer seemed completely composed as she stepped onto the stage"; "I felt calm and more composed than I had in a long time"
discomposed having your composure disturbed; "looked about with a wandering and discomposed air"
dignified having or expressing dignity; especially formality or stateliness in bearing or appearance; "her dignified demeanor"; "the director of the school was a dignified white-haired gentleman"
imperturbable,
unflappable not easily perturbed or excited or upset; marked by extreme calm and composure; "hitherto imperturbable, he now showed signs of alarm"; "an imperturbable self-possession"; "unflappable in a crisis"
equanimous,
self-collected,
self-possessed,
collected,
poised,
self-contained in full control of your faculties; "the witness remained collected throughout the cross-examination"; "perfectly poised and sure of himself"; "more self-contained and more dependable than many of the early frontiersmen"; "strong and self-possessed in the face of trouble"
coolheaded,
nerveless,
cool marked by calm self-control (especially in trying circumstances); unemotional; "play it cool"; "keep cool"; "stayed coolheaded in the crisis"; "the most nerveless winner in the history of the tournament"
