The Clue
Most stiffly proper (8 letter answer)
The Answer
PRIMMEST
Tags
Notes
The answer PRIMMEST is so rare that it appears less than once every 2500 puzzles.
Definition
PRIM as an adjective:
1. (dainty, mincing, niminy-piminy, prim, twee) = affectedly dainty or refined
2. (priggish, prim, prissy, prudish, puritanical, square-toed, straitlaced, strait-laced, straightlaced, straight-laced, tight-laced, victorian) = exaggeratedly proper; "my straitlaced Aunt Anna doesn't approve of my miniskirts"