chevelure
n. a head of hair

abditive
adj. hidden

protreptic
n. a writing intended to exhort or instruct

revolute
v. to imbue with revolutionary spirit

For Histiaeus, when he was anxious to give Aristagoras orders to revolt, could find but one safe way, as the roads were guarded, of making his wishes known; which was by taking the trustiest of his slaves, shaving all the hair from off his head, and then pricking letters upon the skin, and waiting till the hair grew again. Thus accordingly he did; and as soon as ever the hair was grown, he despatched the man to Miletus, giving him no other message than this — ‘When thou art come to Miletus, bid Aristagoras shave thy head, and look thereon.’ Now the marks on the head, as I have already mentioned, were a command to revolt.

— Herodotus, Terpsichore