To erode the base or foundation of something, e.g. by the action of water.
To weaken or work against; to hinder, sabotage.
To dig underneath (something), to make a passage for destructive or military purposes; to sap.
To reduce or gradually eliminate something (such as a debt).
To cut or shape wood with a knife.
To make eager or excited; to excite with liquor; to inebriate.
A knife; especially, a pocket knife, sheath knife, or clasp knife.