1. Important positions or functions that are essential to the success of an organization, project, or endeavor
She played one of the key roles in the company's expansion strategy.
Ela desempenhou um dos papéis-chave na estratégia de expansão da empresa.
2. Leading or principal characters in a film, play, or other performance
The director cast experienced actors for the key roles in the production.
O diretor escalou atores experientes para os papéis-chave na produção.