Word Origin & History
vacillation
c.1400, from L. vacillationem (nom. vacillatio) "a reeling, wavering," from pp. stem of vacillare "sway to and fro." Originally in ref. to opinion or conduct; literal sense is recorded from 1633. Vacillate is attested from 1597 in the sense "to sway unsteadily;" meaning "to waver between two opinions or courses" is recorded from 1623.