IPA: /ˈrɪɡərɪst/
KK: /ˈrɪɡərɪst/
A person who strictly adheres to rules or principles, often in a severe or inflexible manner.
The rigorist insisted on following the rules without exception, even when it seemed unreasonable.
Rigorist → It is formed from "rigor" (from Latin "rigor", meaning stiffness or strictness) and the suffix "-ist" (meaning one who practices or is concerned with). A rigorist is someone who adheres strictly to rules or principles.
Think of someone who is very 'strict' ('rigor') about their beliefs or practices — that's what a rigorist is.