IPA: /kənˈvɪnsər/
KK: /kənˈvɪnsər/
A person or thing that persuades someone to believe or do something.
The convincer used strong arguments to change their minds.
Convincer is formed from "con-" (meaning together) and "vincere" (meaning to conquer or overcome). The word refers to someone who brings others together to overcome doubts or persuade them.
Think of someone who helps you 'overcome' ('vincere') your doubts 'together' ('con-') — that's why a convincer is someone who persuades.