a. [ad. mod.L. type *undulātōri-us: cf. UNDULATE v. and -ORY. So Sp. and Pg. undulatorio, It. ondulatorio, F. ondulatoire.]

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  1.  Of motion: Characterized by successive rise and fall after the manner of waves.

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1728.  Chambers, Cycl., s.v. Undulation, The Undulatory Motion of the Air, is supposed the … Cause of Sound.

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1759.  Phil. Trans., LI. 531. The motion here appeared to be very deep, and was rather undulatory than tremulous.

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1832.  Brewster, Nat. Magic, iv. (1833), 78. A tempest at sea is imitated, by having the sea on one slider, and the ships on other sliders, to which an undulatory movement is communicated.

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1879.  R. H. Elliot, Written on Foreheads, xvi. 149. The translator … tells us that breadth across the hips was considered a great beauty in Hindoo women, and would give an undulatory motion to their walk.

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  b.  Exhibiting, or acting with, undulating motion.

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1794.  R. J. Sulivan, View Nat., I. 169. An elastic fluid … would cause an undulatory diffusion of the luminous particles.

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1813.  J. Thomson, Lect. Inflam., 525. This air … gives an elastic undulatory sensation to the fingers.

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1882.  Gd. Words, June, 382. Vast masses of white cumulus clouds … piled up as in great undulatory breaking billows.

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  c.  Undulatory theory (also hypothesis, † system), the theory that light consists in an undulatory movement of an elastic medium pervading space.

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1802.  Young, in Phil. Trans., XCII. 13. That prepossession which I before entertained for the undulatory system of light.

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1827–8.  Herschel, in Encycl. Metrop. (1845), IV. 449. General Statement of the Undulatory Theory of Light.

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1834.  Mrs. Somerville, Connex. Phys. Sci., xxi. 190. These intervals determine the lengths of the waves on the undulatory hypothesis.

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  2.  = UNDULATING ppl. a. 2 and 2 b.

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1796.  Morse, Amer. Geog., I. 220. The other moccasin snake is … of a pale grey, sky-coloured ground, with brown undulatory ringlets.

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1845.  Darwin, Voy. Nat., xiv. In wooded undulatory districts.

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1853.  G. Johnston, Nat. Hist. E. Bord., I. 51. An undulatory rising ground.

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1884.  in H. Thompson, Tumours Bladder, 94. The deep limit of the growth is clearly defined, convex, undulatory or lobular in character.

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  3.  fig. UNDULATING ppl. a. 1 c.

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1897.  M. L. Hughes, Medit. Fever, 99. The remittent … type of pyrexia of the undulatory or malignant varieties.

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