[f. L. vacillāt-, ppl. stem of vacillāre to sway, stagger, totter, etc., whence also F. vaciller (1314), It. vacillare, Pg. vacillar, Sp. vacilar.]
1. intr. To swing or sway unsteadily; to be in unstable equilibrium; to stagger.
1597. A. M., trans. Guillemeau’s Fr. Chirurg., c j b. Those which are too longe doe vacillate, and turne this way and that way in the hand.
1721. Bailey, To Vacillate, to … stagger, waggle, or shake.
1757. Phil. Trans., L. 505. Whether the earth, during the agitation of the waters, does rock and vacillate,… is what I shall leave to future inquiry.
1802. Paley, Nat. Theol., xxii. When a spheroid … turns upon an axis which is not permanent,… it is always liable to shift and vacillate from one axis to another.
1888. Stevenson, Black Arrow, 175. Lawless, vacillating on his feet, and still shouting the chorus of sea-ballads, took the long tiller in his hands.
b. To vary; to hover doubtfully.
1841. D’Israeli, Amen. Lit. (1867), 231. The fate of books vacillates with the fancies of book-lovers.
1873. Earle, Philol. Eng. Tongue (ed. 2), § 186. Among the words which still vacillate between the two sounds of E A, is the word break.
c. To fluctuate; to produce varying results.
1835. Sir J. Ross, Narr. 2nd Voy., xv. 235. In the course of these attempts at discovering and maintaining the best temperature, it [an apparatus for condensing the vapour] was found to vacillate.
2. To alternate or waver between different opinions or courses of action.
1623. Cockeram, I. Vacillate, to wauer, to be inconstant.
1661. R. Burney, K. Chas. presented, 9. His Majesties wrath … causes the spirit of the ill-affected to vacillate.
1830. D’Israeli, Chas. I., III. ii. 19. In his last years he stood alone, and never less vacillated in his conduct.
1846. Ruskin, Mod. Painters, II. III. iii. § 2. 179, note. He may pause, but he must not hesitate,—and tremble, but he must not vacillate.
1891. Bp. Creighton in Mrs. Creighton, Life (1904), II. i 22. You can judge if you look within; you vacillate if you look without.
b. Freq. const. between.
1827. J. F. Cooper, Prairie, II. xiii. 217. His looks appeared to be strangely vacillating between hope and fear.
1850. McCosh, Div. Govt., II. ii. (1874), 212. The superstitious man vacillates … between hope and fear, between self-confidence and despondency.
