IPA: /ˈɔːɡənɪst/
KK: /ˈɔrɡənɪst/
A musician who plays a large musical instrument called an organ, often found in churches or concert halls.
The organist played a beautiful melody during the wedding ceremony.
Organist → It is formed from "organ" (from Latin "organum", meaning instrument or tool) and "-ist" (meaning one who practices or is concerned with). An organist is one who plays or is concerned with the organ, a musical instrument.
Think of someone who plays an 'instrument' ('organum') — that's why an organist is a person who plays the organ.