Sap(v. t.)
- To make unstable or infirm; to unsettle; to weaken.
Sap(v. i.)
- To proceed by mining, or by secretly undermining; to execute saps.
Sap(n.)
- A narrow ditch or trench made from the foremost parallel toward the glacis or covert way of a besieged place by digging under cover of gabions, etc.