Opacity is the quality of being difficult to see through.
例句
Opacity of the eye lens can be induced by deficiency of certain vitamins...眼球晶狀體的混濁可由缺乏某些維生素造成。He insisted that the mineral content of the water determined the opacity.他堅持認為水的清澈程度取決于其中礦物質的含量。
N-UNCOUNT
費解；難懂；晦澀
If you refer to something's opacity, you mean that it is difficult to understand.
例句
Its dramatic nuances were often generalised to the point of opacity.它那戲劇性的微妙之處常被含糊處理到了晦澀的地步。