Showing no sign of agitation or distress; quite unruffled and unafraid. This expression comes from horse-racing, where a horse that is extremely sweaty shows it in the roughening of its hair. It was transferred, but only in the negative, to human sangfroid in the late nineteenth century. Still referring to its origin, Richard D. Blackmore wrote (Dariel, 1897), “She never turned a hair—as the sporting people say.”