Why is the ninth month called September?
mid-14c., "shelter, defense; keeping, guardianship;" late 14c. as "that which protects," from Old French proteccion "protection, shield" (12c.) and directly from Late Latin protectionem (nominative protectio) "a covering over," noun of action from past participle stem of protegere "protect, cover in front," from pro- "in front" + tegere "to cover" (see stegosaurus).
A common Old English word for "protect" was beorgan. International economic sense is from 1789. In gangster sense, "freedom from molestation in exchange for money," it is attested from 1860. Ecological sense of "attempted preservation by laws" is from 1880 (originally of wild birds in Britain). Also in medieval England, "the protection or maintenance of a lord or patron; sponsorship." To put (someone) out of protection meant to deprive him or her of the security of the protection of the kingdom's laws.