1. A complicated or multifaceted problem that involves many interconnected factors and is difficult to understand or resolve
Climate change is a complex issue that requires global cooperation.
A mudança climática é uma questão complexa que requer cooperação global.
2. A matter or topic that has many layers, nuances, or conflicting perspectives
Healthcare reform remains a complex issue in American politics.
A reforma da saúde continua sendo uma questão complexa na política americana.