pre ‧ vail /prɪˈveɪl/ BrE AmE verb [intransitive not in progressive] formal
[ Date: 1300-1400 ; Language: Latin ; Origin: praevalere , from valere 'to be strong' ]
1 . if a belief, custom, situation etc prevails, it exists among a group of people at a certain time
prevail in/among etc
the economic conditions which prevail in England and Wales
I admired the creativity which prevailed among the young writers.
2 . if a person, idea, or principle prevails in a fight, argument etc, they are successful in the end:
Justice will prevail.
common sense prevails/reason prevails (=a sensible decision is made)
He considered lying, but then common sense prevailed.
prevail over/against
Your inner strength will enable you to prevail over life’s obstacles.
prevail on/upon somebody phrasal verb formal
to persuade someone
prevail on/upon somebody to do something
She prevailed upon her father to say nothing.