prude

/prud/
noun
  1. A person who is easily shocked or offended by things related to sex or nudity, and who behaves in a very proper or modest way.
    • Don't be such a prude — it's just a harmless joke.
    • She was called a prude for refusing to watch the movie's romantic scenes.
    • He felt like a prude when he asked his friends to change the topic.
Antonyms