from
The Collaborative International Dictionary of English v.0.48
Fog \Fog\ (f[o^]g), n. [Dan. sneefog snow falling thick, drift
of snow, driving snow, cf. Icel. fok spray, snowdrift,
fj[=u]k snowstorm, fj[=u]ka to drift.]
1. Watery vapor condensed in the lower part of the atmosphere
and disturbing its transparency. It differs from cloud
only in being near the ground, and from mist in not
approaching so nearly to fine rain. See {Cloud}.
[1913 Webster]
2. A state of mental confusion.
[1913 Webster]
3. (Photog.) Cloudiness or partial opacity of those parts of
a developed film or a photograph which should be clear.
[Webster 1913 Suppl.]
{Fog alarm}, {Fog bell}, {Fog horn}, etc., a bell, horn,
whistle or other contrivance that sounds an alarm, often
automatically, near places of danger where visible signals
would be hidden in thick weather.
{Fog bank}, a mass of fog resting upon the sea, and
resembling distant land.
{Fog ring}, a bank of fog arranged in a circular form, --
often seen on the coast of Newfoundland.
[1913 Webster]