Technical term used in fields such as photography, optics, or materials science to describe the degree to which a substance or medium blocks light. Not commonly used in everyday conversation.
The opacity of this filter is very low, allowing light to pass through well.
Glass with high opacity is used for privacy protection.
Compound of 曇 (cloudiness) and 度 (degree). The exact historical derivation is uncertain, but it follows a common pattern for technical terms indicating a measurable property.