timid

adj

1. Lacking in courage or confidence.

   “John's a very timid person. I doubt he'll be brave enough to face his brother.”

   “When Timothy and Julia hurried up the staircase to the bedroom floor, where a considerable commotion was taking place, Tim took Barry Leach with him.[…]. The captive made no resistance and came not only quietly but in a series of eager little rushes like a timid dog on a choke chain.”