'Opaque' is Latin for 'shaded, dark' — blocking light literally, blocking understanding figuratively.
Not able to be seen through; not transparent or translucent. Figuratively: difficult to understand; obscure or unintelligible.
From Latin 'opācus' (shaded, darkened, covered from light, not transparent), of uncertain ultimate Indo-European origin, though possibly connected to a root for covering or shading. The adjective entered English in the 15th century via medical and scientific Latin, where it described substances that did not transmit light. The abstract meaning — difficult to understand
In computing, 'opacity' describes how non-transparent a visual element is — an opacity of 1.0 means fully opaque, 0.0 means fully transparent. Every time a web designer adjusts CSS opacity to make a button semi-transparent, they are using a Latin word for shade. The antonym 'alpha' (as in alpha channel or alpha transparency) comes from a completely