General English


  • noun condensed water vapour in cloud-like masses lying close to the ground and limiting visibility


  • The visibility and path of the effluent air stream exiting a cooling tower and remaining close to the ground.

Media Studies

  • noun a cloudy area on a photographic image, caused by too much light
  • verb to produce a cloudy image on a negative, print or transparency by allowing too much light to reach it in the developing process


  • noun a thick cloud of water vapour at ground level, which reduces visibility


  • noun the effect on photographic material that has been accidentally exposed to light, causing a loss of picture contrast

Origin & History of “fog”

The word fog is something of a mystery. It first appears in the 14th century meaning ‘long grass’, a use which persists in Yorkshire fog, the name of a species of grass. This may be of Scandinavian origin. The relationship, if any, between fog ‘grass’ and fog ‘mist’ is not immediately clear, but it has been speculated that the adjective foggy, which to begin with referred to places overgrown with long grass, and then passed via ‘of grassy wetlands’ to ‘boggy, marshy’ may have given rise via this last sense to a noun fog denoting the misty exhalations from such marshy ground. A rather far-fetched semantic chain, perhaps, lacking documentary evidence at crucial points, and perhaps Danish fog ‘spray, shower’ may be closer to the real source.