IPA: /prəˈlɒkjʊtə/
KK: /proʊˈlɒkjʊtər/
A person who speaks on behalf of someone else or leads a meeting, especially in a formal setting.
The prolocutor guided the discussion during the church convocation.
Prolocutor is formed from "pro-" (meaning for or in favor of) and "locutor" (from Latin "loqui", meaning to speak). The word refers to someone who speaks on behalf of others or represents a group in discussions.
Think of someone who speaks 'for' ('pro-') others — that's why a prolocutor is a representative speaker.