killjoy

UK: ˈkɪldʒɔɪ | US: ˈkɪlˌdʒɔɪ

Definition
  1. n. a person who deliberately spoils the enjoyment of others

  2. n. someone who dampens enthusiasm or fun

Structure
kill <destroy>joy <happiness>
Etymology

The word "killjoy" is a compound formed by combining "kill" (from Old English cwellan, meaning "to destroy") and "joy" (from Old French joie, meaning "happiness"). It emerged in the early 19th century to describe a person who ruins others' pleasure, reflecting a vivid metaphor of "killing" happiness. The structure is transparent, making it easy to decode: someone who "kills joy."

Examples
  1. Don’t be such a killjoy—let’s celebrate!

  2. He refused to join the party, earning a reputation as the office killjoy.

  3. The strict teacher was seen as a killjoy by the students.

  4. She didn’t mean to be a killjoy, but her criticism ruined the mood.

  5. The rain turned him into a killjoy during the picnic.