Source : Webster's Revised Unabridged Dictionary (1913)

Havelock \Hav"e*lock\, n. [From Havelock, an English general
   distinguished in India in the rebellion of 1857.]
   A light cloth covering for the head and neck, used by
   soldiers as a protection from sunstroke.

Source : WordNet®

havelock
     n : a cloth covering for a service cap with a flap extending
         over the back of the neck to protect the neck from direct
         rays of the sun