scarcement

from The Century Dictionary.

• noun In building, a setback in the face of a wall, or in a bank of earth; a footing or ledge formed by the setting back of a wall.
• noun In mining, a small projecting ledge left in a shaft as a temporary support for a ladder, or for some similar purpose.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Arch. & Engin.) An offset where a wall or bank of earth, etc., retreats, leaving a shelf or footing.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun architecture, engineering An offset where a wall or bank of earth, etc., retreats, leaving a shelf or footing.