1. impossible to bear or endure; intolerable
2. impossible to justify or defend

Examples

• The heat in the desert became insupportable by midday.
• His arrogant behavior was insupportable to his colleagues.
• The pain from her injury was insupportable without medication.
• The politician’s claims were insupportable given the evidence.
• Living conditions in the overcrowded shelter were insupportable.
• Her theory was insupportable without proper research data.