As a part of their costume, French nobles of the late Middle Ages wore a kind of hood, not unlike the hood that is a part of the academic gown of today.
It somewhat resembled the mantle, chape, worn by priests and others of that period, and for that reason the hood was called a chaperon, little mantle.
In England, when Edward III founded the Order of the Garter, in 1349, the chaperon was a part of the full-dress costume worn by the members. Except by these members, however, this hood was not worn by men after the fifteenth century.
It was then taken up by ladies, especially by those of the court.
Ultimately, but not before the eighteenth century, the term acquired its present general sense, which has thus been explained: “When used metaphorically (it) means that the experienced married woman shelters the youthful debutante as a hood shelters the face.”