[ad. L. type *undulāt- (cf. prec.), ppl. stem of *undulāre, f. unda. Cf. Sp. and Pg. undular, It. ondulare, F. onduler.]
1. intr. To move in, or after the manner of, waves; to have a wave-like motion.
1664. Power, Exp. Philos., I. 69. The former Experiment of the Snail,… whose Animal Spirits never begin to undulate till she begin to move.
1721. Bailey, To Undulate, to roll as waves do.
1796. H. Hunter, trans. St.-Pierre’s Stud. Nat. (1799), II. 41. The … swallow is continually skimming along their surface, undulating like the waters of a lake.
1820. Shelley, To M. Gisborne, 120. The ripe corn under the undulating air Undulates like an ocean.
1869. J. Phillips, Vesuv., ix. 253. The water undulates, the land vibrates.
b. transf. Of sound, etc.
1760–72. H. Brooke, Fool of Qual. (1809), IV. 158. An universal shout … followed and undulated after our company.
1784. Cowper, Task, I. 175. Tall spire, from which the sound of cheerful bells Just undulates upon the list’ning ear.
1818. Shelley, Rosalind, 833. The light serene Of smiles, whose lustre bright and soft Beneath lay undulating there.
c. To float on waves. Also fig.
1813. H. & J. Smith, Horace in Lond., 24. He undulates on Ocean’s swell.
1891. T. Hardy, Tess, xix. She undulated upon the thin notes [of the harp] as upon billows.
2. trans. a. To cause to move, esp. to rise and fall, after the manner of waves.
1669. Holder, Elem. Speech, 47. It may very well be, that Breath vocalized, i.e. vibrated or undulated, may in a different manner affect the Lips.
1725. Fam. Dict., s.v. Hot-bath, Like a Fomentation, which … by gently shaking and undulating the Fibres, helps forwards those animal Motions.
1865. Intell. Observ., Sept., 84. A snail-leech … attaching its suckers to the glass vessel in which it is confined, and … undulating the intervening portion of the body.
1873. Leland, Egypt. Sketch-Bk., 135. The first dancing of all Ghawâzi is simply moving about to the music and undulating the body.
b. To invest with the form or appearance of a wavy or rippling surface.
1730. A. Gordon, Maffei’s Amphith., 351. The red … and yellow Coverings of the Theatre, reflected back on the Assembly of Spectators,… undulating the whole with their Colours.
1804. Shaw, Gen. Zool., V. 419. The body is obliquely undulated by twelve lines of the same colour.
1843. trans. Custine’s Empire of Czar, I. 216. It is for man to build mountains, when nature has not undulated the surface of the earth.
3. intr. To present a wavy surface or outline.
1833. L. Ritchie, Wand. by Loire, 255. The vast plain undulates in hills and valleys.
1849. Ruskin, Sev. Lamps, v. § 13. 149. There is not one of the arches the same in height as another; their tops undulate all along the wall.
1866. Geo. Eliot, F. Holt, i. A … masculine face, with rich brown hair … undulating beside each cheek.
b. To have the effect of waves to the eye.
1888. H. W. Parker, Spirit of Beauty, 220. Silks of changing hues that undulate like a purple sunset on a billowy sea.
