- cool, coolheaded, nerveless - 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"
Antonym: discomposed (indirect, via composed)
- feeble, nerveless - lacking strength; "a weak, nerveless fool, devoid of energy and promptitude"- Nathaniel Hawthorne
Antonym: powerful (indirect, via powerless)