Source : Webster's Revised Unabridged Dictionary (1913)

Horripilation \Hor*rip`i*la"tion\, n. [L. horripilatio, fr.
   horripilare to bristle; horrere to bristle + pilus the hair:
   cf. F. horripilation.] (Med.)
   A real or fancied bristling of the hair of the head or body,
   resulting from disease, terror, chilliness, etc.

Source : WordNet®

horripilation
     n : reflex erection of hairs of the skin in response to cold or
         emotional stress or skin irritation [syn: {pilomotor
         reflex}, {gooseflesh}, {goose bump}, {goose pimple}, {goose
         skin}]