Sap | Webster's Dictionary (1865)

Sāp, n.

noun

n. [A-S. sāp, L. Ger. sapp, D. sap, O. H. Ger. saft, N. H. Ger. saft, Icel. saft, Sw. saft, saf, safra, Dan. saft, säve; Lat. sapa, must or new wine boiled thick.] 1. The juice of plants of any kind, especially the ascending and descending juices essential to nutrition. ☞ The ascending is the crude sap, the assimilation of which takes place in the leaves, when it becomes the elaborated sap suited to the growth of the plant.

(Bot.) The alburnum of a tree; the exterior part of the wood, next to the bark; sap-wood.
A simpleton; a sap-head. [Colloq. or cant.]

Sāp, v. t.

verbtransitive

v. t. [imp. & p. p. SAPPED (sāpt); p. pr. & vb. n. SAPPING.] [Fr. saper, Sp. zapar, It. zappare, probably from Gr. σκάπτειν, σκάπτειν, to dig.]

Sense 1. To subvert by digging or wearing away; to mine; to undermine; to destroy the foundation of. Their dwellings were sapped by floods. Dryden.

Sense 2. (Mil.) To pierce with saps.

Sāp, v. i.

verbintransitive

v. i. 1. To proceed by mining, or by secretly undermining.

Both assaults are carried on by sapping. Tatler.

Sense 2. (Mil.) To execute saps. Craighill.

Sāp, n.

noun

(Mil.) An approach made to a fortified place by digging under cover of gabions, &c.

☞ The single sap has only a single parapet; the double has one on each side. In all saps, traverses are left to cover the men.