Synonyms: nerveless, cool, coolheaded
Definition: marked by calm self-control (especially in trying circumstances); unemotional
Usage: play it cool; keep cool; stayed coolheaded in the crisis; the most nerveless winner in the history of the tournament
Similar words: composed
Definition: serenely self-possessed and free from agitation especially in times of stress
Usage: the performer seemed completely composed as she stepped onto the stage; I felt calm and more composed than I had in a long time