adjectives
lacking sensation
"my foot is asleep"; "numb with cold"
(followed by `to') not showing human feeling or sensitivity; unresponsive
"passersby were dead to our plea for help"; "numb to the cries for mercy"
so frightened as to be unable to move; stunned or paralyzed with terror; petrified
"too numb with fear to move"
is similar to
filled with fear or apprehension
"afraid even to turn his head"; "suddenly looked afraid"; "afraid for his life"; "afraid of snakes"; "afraid to ask questions"