1. A subject or issue that is widely discussed, accepted, or relevant to the general public and dominant culture
Climate change has become a mainstream topic in political debates.
As mudanças climáticas tornaram-se um tópico principal nos debates políticos.
2. A subject that receives significant coverage in major media outlets and is considered socially acceptable for discussion
Mental health is now a mainstream topic in workplace conversations.
A saúde mental agora é um assunto mainstream nas conversas do local de trabalho.