1. the quality or state of being opaque; not allowing light to pass through
2. the quality of being difficult to understand or explain; obscurity

Examples

• The opacity of the frosted glass provided privacy for the office.
• The window’s opacity increased as condensation formed on the surface.
• The opacity of the legal document made it hard for ordinary citizens to understand.
• Scientists measured the opacity of different materials to determine their light-blocking properties.
• The professor criticized the opacity of the student’s writing style.
• The opacity of the government’s decision-making process frustrated voters.