/oʊˈpæsəti/
n. 不透明；不传导；暧昧
Opacity refers to the degree of transparency or translucency of an object or material. In the context of digital design, graphics, or web development, it describes how much light can pass through an element. A value of 0 for opacity means the element is completely transparent (invisible), while a value of 1 (or 100% in some notations) means the element is completely opaque (fully visible). For example, in CSS, you can set the opacity of a div element like this: “div {opacity: 0.5;}” which makes the div semi - transparent, allowing the content behind it to be somewhat visible. In image editing software, adjusting the opacity of a layer can blend it with the layers beneath in different ways.