terreplein

Etymology
Originally a borrowing of, later altered after the model of (now ). Its former misspellings arose from confusion of the second element of the name with Italian or French,  based on the appearance of the earth-filled central platforms of walls.

Noun

 * 1)  The sloping earthen embankment behind a defensive wall.
 * 2)  The level platform atop a wall, typically protected by a parapet and  distinguished from the slightly higher banquette used by its defenders.
 * 3)  Any level base used by artillery in the field.
 * 4)  Any earthen embankment with a broad level top, such as those used for a canal elevated above a valley floor.