recoil

To recoil is to spring back or back away.

(verb)

When you jump backwards in horror away from a dead body you have just spotted, this is an example of recoil.
When a gun kicks back when fired, this is an example of recoil.

See recoil in Webster's New World College Dictionary

intransitive verb

1. to draw back, fall back, or stagger back; retreat
2. to start or shrink back, as in fear, surprise, or disgust
to fly back when released, as a spring, or kick back when fired, as a gun
to return to or as to the starting point or source; react (on or upon)

Origin: ME recoilen < OFr reculer < re-, back + cul < L culus, the anus, buttocks: see culet

noun

See recoil in American Heritage Dictionary 4

intransitive verb re·coiled, re·coil·ing, re·coils

To spring back, as upon firing.
To shrink back, as in fear or repugnance.
To fall back; return: “Violence does, in truth, recoil upon the violent” (Arthur Conan Doyle).

noun also (rēˈkoilˌ)