Sap

sap, v. [sapped (sapt), -ping.] To subvert by digging or wearing away to mine, undermine. {Mil.) To pierce with saps. v. To proceed by mining, or by secretly undermining. — n. (Mil.) An approach made to a fortified place by digging under cover of gabions, etc. [OF. sapper, sappe, LL. sap a, a hoe, digging implement.] — Sap'per,