Trepidation

Noun

1. Anxiety over the uncertain future or possible ill-occurrence.

   "I decided, with considerable trepidation, to let him drive my car without me."

2. An involuntary trembling, sometimes an effect of paralysis, but usually caused by terror or fear.
3. 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.