IPA: /ˈprɪmɪst/
KK: /ˈprɪmɪst/
The highest degree of being neat, proper, or formal.
She always dresses in the primmest way for formal events.
Comparative: primmer
Superlative: primmest
Primmest is derived from "prim" (from Old French *prim*, meaning first or primary) and the suffix "-est" (used to form the superlative). The word "primmest" means the most prim or the most proper, indicating the highest degree of being prim.
Think of 'prim' meaning first or proper, and remember that 'primmest' refers to the highest degree of being proper.