mass noun
1- a thick cloud of tiny water droplets suspended in the atmosphere at or near the earth's surface which obscures or restricts visibility (to a greater extent than mist; strictly, reducing visibility to below 1 km)雾：
the collision occurred in thick fog.
碰撞发生在有浓雾时。
1.1
- in sing. an opaque mass of something in the atmosphere烟雾, 尘雾：
a whirling fog of dust.
尘雾旋涡。
1.2
- in sing. figurative something that obscures and confuses a situation or someone's thought processes〈喻〉搅乱形势（或思维）的事：
the origins of local government are lost in a fog of detail.
地方自治的由来堕入细枝末节的云雾之中, 难以考证。
1.3
- Photography cloudiness which obscures the image on a developed negative or print【摄】（底片等的）灰雾, 雾翳。
(fogged, fogging)with obj.
1
- cause (a glass surface) to become covered with steam使（玻璃表面）起雾：
hot steam drifted about her, fogging up the window.
她周围一片热蒸汽, 窗玻璃也起了雾。
1.1
- no obj.(of a glass surface) become covered with steam（玻璃表面）起雾：
the windscreen was starting to fog up.
挡风玻璃开始起雾。
1.2
- figurative bewilder or puzzle (someone)〈喻〉使迷惑, 使不解：
she stared at him, confusion fogging her brain.
她凝视着他, 脑子里一团雾水。
1.3
- figurative make (an idea or situation) difficult to understand〈喻〉使（想法, 形势）难以理解：
the government has been fogging the issue.
政府一直在搅浑这个问题。
1.4
- Photography make (a film, negative, or print) obscure or cloudy【摄】使（胶片, 底片, 照片）变得不清晰, 使产生雾翳。
2
- treat with something, especially an insecticide, in the form of a spray用喷雾（尤指杀虫剂）喷。
短语
in a fog
- in a state of perplexity; unable to think clearly or understand something困惑不解, 如坠五里雾中。
词源
mid 16th cent.: perhaps a back-formation from FOGGY.