an involuntary trembling, sometimes an effect of paralysis, but usually caused by terror or fear; quaking; quivering.-hence, a state of terror or alarm; fear; confusion; fright; as, the men were in great trepidation.-a libration of the starry sphere in the ptolemaic system; a motion ascribed to the firmament, to account for certain small changes in the position of the ecliptic and of the stars.