1. impossible to attack, question, or defeat; beyond doubt or criticism

Examples

• Her reputation for honesty was unassailable.
• The fortress was built in an unassailable position on the mountaintop.
• The evidence against the defendant was unassailable.
• His argument was so well-researched that it seemed unassailable.
• The team held an unassailable lead in the final minutes.
• The scientist’s theory was supported by unassailable data.
• The castle’s unassailable walls had never been breached.