marplot

/ˈmɑrplɑt/
noun
  1. A person who spoils or ruins a plan or activity by interfering or making mistakes.
    • The team's new member turned out to be a marplot, accidentally deleting important files.
    • She tried to help, but her constant suggestions made her a marplot in the kitchen.
    • Every group project has one marplot who derails the discussion with off-topic questions.
Antonyms
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