prim

/prɪm/
adjective
  1. Very proper, formal, and careful about one's behavior or appearance, often in a way that seems stiff or overly correct.
    • My aunt is so prim that she never laughs loudly or tells jokes.
    • He gave a prim little smile and adjusted his tie before answering.
    • The prim librarian always wore her hair in a tight bun and spoke in a quiet voice.
Antonyms
verb
  1. To make oneself look neat, tidy, or formal, often with small adjustments to clothing or appearance.
    • She primmed her dress and checked her reflection before the interview.
    • The children primmed themselves before the school photo.
    • He primmed his collar and smoothed his hair before stepping onto the stage.