Толковый словарь английского языка Oxford English Reference - sap

1. n. & v. --n. 1 the vital juice circulating in plants. 2 vigour; vitality. 3 = SAPWOOD. 4 US sl. a bludgeon (orig. one made from a sapling). --v.tr. (sapped, sapping) 1 drain or dry (wood) of sap. 2 exhaust the vigour of (my energy had been sapped by disappointment). 3 remove the sapwood from (a log). 4 US sl. hit with a sap. Phrases and idioms sap-green n. 1 the pigment made from buckthorn berries. 2 the colour of this. --adj. of this colour. Derivatives sapful adj. sapless adj. Etymology: OE s{aelig}p prob. f. Gmc 2. n. & v. --n. 1 a tunnel or trench to conceal assailants' approach to a fortified place; a covered siege-trench. 2 an insidious or slow undermining of a belief, resolution, etc. --v. (sapped, sapping) 1 intr. a dig a sap or saps. b approach by a sap. 2 tr. undermine; make insecure by removing the foundations. 3 tr. destroy insidiously. Etymology: ult. f. It. zappa spade, spadework, in part through F sappe sap(p)er, prob. of Arab. orig. 3. n. sl. a foolish person. Etymology: abbr. of sapskull f. SAP(1) = sapwood + SKULL