costly
expensive / ruinous / dear
Adjective
comp: costliersup: costliest
This term describes a high price paid, whether in currency or in human life and effort. It carries a heavier weight than expensive, often implying that the price paid was excessive, regrettable, or disproportionate to the value received. When used to describe losses or mistakes, it suggests a permanent or severe consequence. A costly error is not merely a financial setback but a failure that results in significant damage or a strategic disadvantage.