1. A topic or matter of great importance, significance, or seriousness that deserves careful consideration
Climate change is a weighty subject that affects all nations.
Mudanças climáticas são um assunto importante que afeta todas as nações.
2. A discussion or issue that carries substantial consequences or ethical implications
We need to address the weighty subject of healthcare reform.
Precisamos abordar o assunto grave da reforma da saúde.