IPA: /dɪˈbeɪtə/
KK: /dɪˈbeɪtər/
A person who takes part in a discussion or argument about a particular topic, often presenting opposing viewpoints.
The debater presented strong arguments to support her position on climate change.
Debater → It is formed from "debatere" (from Latin, meaning to discuss or argue) and "-er" (meaning a person who). A debater is a person who engages in discussion or argument.
Think of someone who is 'discussing' or 'arguing' ('debatere') — the '-er' just means a person. A debater is someone who participates in a debate.