1911 Encyclopædia Britannica/Sap

SAP. (1) Juice, the circulating fluid of plants (see Sap, § Physiology). The word appears in Teutonic languages, cf. Ger. Saft, and may be connected ultimately with the root seen in Lat. sapere, taste, hence to know, cf. sapientia, wisdom, cf. Gr. σοφός, wise. On the other hand it may, like Fr. sève, Span. saba, have come direct from Lat. sapa, must, new wine, itself also from the same root. The Gr. ὀπός is represented in Lat. by sucus. (2) A military term for a trench dug by a besieging force for the purpose of approach to the point 'of attack when within range, hence “ to sap,” to undermine, dig away the foundations of a wall, &c. The word is derived through the Old Fr. from the Med. Lat. sapa, sappa, a spade, entrenching tool, Gr. σκαπάνη, σκάπτειν to dig. (See Fortification and Siege-craft.)