prevail

The core sense, and the one the Latin spells out: praevaleō, from prae "before" and valeō "be able or powerful," so to prevail was to be more able than a rival. The King James Bible of 1611 uses it with no object at all: "Israel prevailed; … Amalek prevailed." The verb still works that way, with against naming the opponent when needed. It can also mean simple predominance, as when one color prevails in a flag.

Here the struggle is over and someone has won. The "upper hand" sense can describe an advantage that comes and goes, but this one names the outcome, which makes it natural in predictions about contests still underway: the MI6 chief was "optimistic" that Ukraine would prevail against the Russian invasion. Against introduces the loser, and the winner can be abstract, as in a parallel world "in which death prevailed."

No contest is involved: what prevails is simply what is found most widely, and a phrase of time or place usually marks where, as in "all over Europe" or "in his day and age." The present participle prevailing also works as an adjective before a noun, as in the prevailing winds or the prevailing mood.

The persuading sense needs a preposition: one prevails on or upon a person, and an infinitive says what they were brought to do, as in "I prevailed on him to wait." Henry Fielding's The History of Tom Jones (1749) lets it stand alone once the target is clear: after pressing the lady to unmask, Jones, "having prevailed," finds she is Lady Bellaston. Without on or upon, readers will hear the "triumph" meaning instead.