| 释义 |
undulation|ʌndjʊˈleɪʃən|
[ad. med. or mod.L. *undulātio: cf. undulate a. and v., and Sp. undulacion (Pg. -açāo), F. ondulation, It. ondulazione.]
1. The action of moving in a wave-like manner; a gentle rising and falling in the manner of waves.
1646Sir T. Browne Pseud. Ep. iii. xv. 142 Those animals, whose bodies consist of..annulary fibers, and move by undulation, that is, like the waves of the Sea. 1664Power Exp. Philos. i. 36 Their motion is..restless and constant, with perpetual undulations and wavings, like Eels or Snakes. 1707Floyer Physic. Pulse-Watch 267 The undulation of the Spirits towards the Brain produces all our Sensations. 1762Falconer Shipwreck i. 308 Soon this transient undulation o'er The sea subsides. 1820Keats Hyperion iii. 132 His golden tresses..Kept undulation round his eager neck. 1854Owen in Orr's Circ. Sci., Org. Nat. I. 228 Whales and porpoises progress by bounding movements or undulations in a vertical plane. 1875Manning Mission H. Ghost iv. 106 We are as unstable as..the restless undulation of the water.
transf.
1777Johnson Lett. I. 389 Mrs. * * grows old, and has lost much of her undulation and mobility.
b. A wave-like motion of the air, ‘ether’, etc., as in the propagation of sound or light.
1658Phillips s.v., Undulation of the air. 1672Phil. Trans. VII. 5148 The other Secondary Affections of Winds; as their Undulation,..Opposition, etc. 1728Chambers Cycl. s.v. Sound, A Wave or Undulation of Air. 1764Reid Inquiry iv. §1. 117 Each undulation must be made up of the advance and recoil of innumerable particles of elastic air. 1802Young in Phil. Trans. XCII. 21 The undulations of green light being nearly in the ratio of 6½. 1870H. Spencer Princ. Psych. I. i. iii. 47 Those minute agents that terminate the nerves of the retina are acted on by luminiferous undulations.
Comb.1838Whewell in Todhunter Acc. Writ. (1876) II. 269 A curious..paper upon the theory of the rainbow treated undulation-wise.
c. transf. Of sound.
1668Dryden Ess. Dram. Poesy ⁋3 Those little undulations of sound..still seeming to retain somewhat of their first horror. 1705Addison Italy 42 Two parallel Walls that beat the Sound back on each other, till the Undulation is quite worn out. 1791Mrs. Radcliffe Rom. Forest xi, The notes floated on the air in soft undulations. 1851Froude Short Stud., Homer (1867) II. 166 The actions of men..crumble away into the softer undulations of prose.
†d. spec. (See quot.) Obs.—1
1676Grew Musæ um, Anat. Stomach vi. 25 Vndulation, is when the Contraction is made in several parts of the Stomach successively.
2. A wave-like curve or a series of these; an undulating curvature or sweep.
1670Evelyn Sylva (ed. 2) 119 The Root of the wilder sort [is] incomparable for its crisped undulations. 1803Shaw Gen. Zool. IV. 497 Scales..edged with yellow, so as to form numerous obliquely transverse undulations over the whole body. 1846Carpenter Man. Phys. 186 Minute tubuli,..exhibiting numerous minute undulations, and sometimes more decided curvatures, in their course. 1875T. Seaton Fret-Cutting 36 How..you will turn or bend the stalks, so as to give a natural undulation and appearance to the whole work.
3. The fact of forming or presenting a series of rounded heights and hollows; an undulating rise and fall of level.
1798S. & Ht. Lee Canterb. T. II. 441 For many a mile, with graceful undulation, wandered the high road. 1835Willis Pencillings I. xxiv. 167 A continual undulation of rock and sand.
b. An instance of this; also, a single rise and fall of this nature.
1823Rutter Fonthill 86 The undulations of the surface occasionally give a beautiful variety to the scene. 1878Huxley Physiogr. 214 Here the strata..have been thrown into a succession of gentle undulations. |