1. in a way that cannot be justified or forgiven

Examples

• The teacher was inexcusably late to class without any explanation.
• His behavior at the wedding was inexcusably rude.
• The company inexcusably ignored safety regulations.
• She was inexcusably careless with the important documents.
• The delay in emergency response was inexcusably long.
• He inexcusably broke his promise to help with the project.