Meaning of “prim” - Learner’s Dictionary

prim

adjective uk us /prɪm/

Someone who is prim behaves in a very formal way and is easily shocked by anything rude:

Sarah wouldn't find that funny - she's far too prim and proper (= shocked by anything rude).
primly adverb

(Definition of “prim” from the Cambridge Learner’s Dictionary © Cambridge University Press)