Fear:

1. a distressing emotion aroused by impending danger, evil, pain,    etc., whether the  threat is real or imagined; the feeling or condition of being afraid. (www.dictionary.com)

2. Missing the last step on a staircase. Leaning too far back in your chair. Spiders. Horror movies. Rollercoasters. Bolting up the stairs after turning the light off. That one nightmare you keep having. Darkness. A shadow dancing just out of sight. Forgetting how to breathe. Disease. Feeling fine, but knowing you must be dying. "It's cancer." Remembering how to breathe, but your lungs won't hold enough air. Death. Seeing someone about to give up a fight. Shaking hands, breath, and voice. "She's gone." The feeling you get at night when you have no one to wear your mask for and you realize that you are alone.