IPA: /pɑːrˈtɪʃənɪst/
KK: /pɑrˈtɪʃənɪst/
A person who supports the division of a country into separate parts or regions.
The partitionist argued for the separation of the two regions to ensure peace.
Partitionist → It is formed from "partition" (from Latin "partitio", meaning division) and "-ist" (meaning one who practices or is concerned with). A partitionist is someone who advocates for or supports division or separation.
Think of someone who is concerned with 'division' ('partition') — that's why a partitionist is someone who supports dividing things.