| 释义 |
jump-off|ˈdʒʌmpɒf, -ɔːf|
[f. to jump off.]
1. A precipitous descent; a place from which a person must jump. U.S. colloq.
1873[see bed n. 12 f]. 1884C. Phillipps-Wolley Trottings of Tenderfoot v. 129 The broad stem of a fallen giant gives you 150 feet of splendid wooden road; but..you find you have been gradually ascending, and now stand on what the Americans would call a ‘jump off’. 1909R. A. Wason Happy Hawkins ii. 26 The lantern shed a splash o' light on the shelf, but the jump-off looked like the mouth o' the pit.
b. The start of a military operation or campaign. U.S. slang.
1918[see H-Hour s.v. H III]. 1944Daily Progress (Charlottesville, Va.) 12 May 1/8 The Fifth and Eighth armies have launched the greatest drive in Mediterranean warfare in the jump-off of Allied spring offensives. 1945Sun (Baltimore) 23 Feb. 1/6 (heading) Canadians find going toughest since jumpoff.
2. Aeronaut. A vertical take-off.
In quot. 1969 ‘jump off point’ = jumping-off point.
1939Jrnl. R. Aeronaut. Soc. XLIII. 110 (heading) Possibilities of the jump-off autogyro. Ibid., The available kinetic energy in the rotor system for ‘jump-off’ is directly proportional to the weight of the blades and to the square of the rotational speed of the rotor. 1969Daily Tel. 16 Jan. 1/6 A space station in permanent orbit round the earth..could..be used as a ‘jump off’ point for travel to the moon.
3. Show-jumping. An additional round to resolve or determine a tie.
1947H. Disston Equestionnaire (rev. ed.) 77 In the event of a jump off over triple bars, how is the obstacle altered? 1954P. Smythe Jump for Joy vii. 113 The final jump-off included a high wall with a pole on top. 1969Times 10 May 6/5 Alan Oliver..justified..the odds laid on him in the..competition yesterday. Riding Pitz Palu, who was made favourite at 7-2 and shortened to 2-1 for the jumpoff, he..made the running from start to finish. |