noun \ˈfg, fäg\

: many small drops of water floating in the air above the ground, the sea, etc.

: a state of mental confusion

Full Definition of FOG

a :  vapor condensed to fine particles of water suspended in the lower atmosphere that differs from cloud only in being near the ground
b :  a fine spray or a foam for firefighting
:  a murky condition of the atmosphere or a substance causing it
a :  a state of confusion or bewilderment <spent the morning in a fog>
b :  something that confuses or obscures <hid behind a fog of rhetoric>
:  cloudiness or partial opacity in a developed photographic image caused by chemical action or stray radiation
fog·less \-ləs\ adjective

Examples of FOG

  1. Heavy fog made it difficult to see the road.
  2. a climate marked by heavy fogs
  3. The fog reduced visibility to a quarter of a mile.
  4. This problem has me in a fog.

Origin of FOG

probably back-formation from foggy
First Known Use: 1544

Rhymes with FOG



: to cover or fill (something) with small drops of water : to make (something) foggy

: to become foggy

: to make (someone or something) confused


Full Definition of FOG

transitive verb
:  to cover, envelop, or suffuse with or as if with fog <fog the barns with pesticide>
:  to make obscure or confusing <accusations which fogged the real issues>
:  to make confused
:  to produce fog on (as a photographic film) during development
intransitive verb
:  to become covered or thick with fog
a :  to become blurred by a covering of fog or mist
b :  to become indistinct through exposure to light or radiation

Examples of FOG

  1. The steam from the pot was fogging the window near the stove.
  2. The bathroom was all fogged up after my shower.
  3. politicians who try to fog the issue instead of taking a stand

First Known Use of FOG



transitive verb \ˈfäg, ˈfg\   (Medical Dictionary)

Medical Definition of FOG

: to blur (a visual field) with lenses that prevent a sharp focus in order to relax accommodation before testing vision


noun    (Concise Encyclopedia)

Cloud of small water droplets near ground level that is dense enough to reduce horizontal visibility to less than about 3,000 ft (1,000 m). Fog may also refer to clouds of smoke particles (smog), ice particles, or mixtures of these components. When visibility is more than 3,000 ft, the phenomenon is termed mist or haze, depending on whether it is caused by water drops or by solid particles. Fog is formed by the condensation of water vapour on condensation nuclei that are always present in natural air. The most stable fogs occur when the surface is colder than the air above. Fogs can also occur when cold air moves over a warm, wet surface and becomes saturated by the evaporation of moisture from the surface. Convection currents carry the fog upward as it forms, and it appears to rise as steam or smoke from the wet surface.


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