What is the meaning of Terreplein?

The sloping earthen embankment behind a defensive wall.

The level platform atop a wall, typically protected by a parapet and distinguished from the slightly higher banquette used by its defenders.

Any level base used by artillery in the field.

Any earthen embankment with a broad level top, such as those used for a canal elevated above a valley floor.

Alternative form of terre-plein

Source: wiktionary.org