E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The sloping mass on the outer edge of the covered way in fortification. Immediately without the ditches of the place fortified, there is a road of communication all round the fortress (about thirty feet wide), having on its exterior edge a covered mass of earth eight feet high, sloping off gently towards the open country. The road is technically called the covered way, and the sloping mass the glacis.