A thick cloud of tiny water droplets suspended in the atmosphere at or near the earth's surface, which obscures or restricts visibility. The morning fog made it difficult to see the road ahead.
A state of mental confusion or lack of clarity. After the long meeting, he felt like he was in a fog and couldn't concentrate on his work.
A veil or haze that appears on photographic film or prints as a result of unintended exposure or chemical action. Poor dark-room technique can leave a noticeable fog on the negatives.
A fine aerosol of insecticide, disinfectant, or similar substance used to fill an enclosed space for pest control or sanitation. The cleaning crew released a disinfectant fog throughout the office overnight.