fog

Meanings

1. 1noununcountable

   A thick cloud of tiny water drops that hangs close to the ground and makes it hard to see far.

   Grammar: No plural and no 'a' in this weather sense: we say 'thick fog', not 'a fog' or 'fogs'.

   Patterns

   • thick/dense fog
   • fog clears/lifts
   • in the fog

   Thick fog covered the airport, so all morning flights were delayed.

   We drove slowly because the fog made it impossible to see more than ten meters ahead.

   The fog lifted around noon and the mountains appeared again.

2. 2nounsingularfigurative

   A confused state of mind in which you cannot think or remember clearly.

   Grammar: Usually used as 'a fog' with a describing phrase after it: a fog of tiredness, a fog of grief.

   Patterns

   • a fog of something
   • in a fog
   • clear the fog

   After two nights without sleep, his thoughts were in a fog.

   She walked through the first weeks of grief in a fog of disbelief.

   A strong coffee helped clear the fog from my head.

3. 3verbtransitive or intransitive

   To cover a surface with steam or mist so that you cannot see through it.

   Grammar: Often used with 'up': the mirror fogged up. Takes an object when you name the surface: steam fogged the windows.

   Patterns

   • fog up
   • fog something up
   • something fogs over

   The bathroom mirror fogged up while the shower was running.

   His glasses fogged over as soon as he stepped into the warm kitchen.

   Breathing on the cold window fogged the glass.

4. 4verbtransitivefigurative

   To make something unclear or difficult to understand.

   Grammar: Takes an object, often a word like 'issue', 'memory' or 'picture': emotions fogged his judgment.

   Patterns

   • fog the issue
   • fog someone's memory/judgment

   Anger had fogged his judgment, and he said things he later regretted.

   Too many details can fog the main point of a report.

   Painkillers had fogged her memory of that afternoon.

Word forms

Common combinations

thick fog

Thick fog shut down the highway for three hours.

dense fog

Dense fog is common along this coast in early morning.

fog lifts

The fog lifted just before sunset.

patchy fog

The forecast warns of patchy fog overnight.

in a fog

He wandered around in a fog for days after the accident.

Synonyms and how they differ

mist

Mist is thinner and lighter than fog and usually lets you see further; use 'mist' for a gentle spray or light haze, 'fog' for thick, sight-blocking cloud.

haze

Haze is a dim, dusty or smoky blur in the air, often from heat or pollution, and is less wet than fog.

smog

Smog is fog mixed with smoke or pollution, so use it only when the air is dirty, not for clean weather fog.

Opposites

Word family

foggy adjective

Full of fog, or unclear: a foggy morning; a foggy memory.

foggily adverb

In a confused or unclear way: he explained it foggily.

fogbound adjective

Unable to travel because of fog: a fogbound airport.

defog verb

To remove mist or condensation from glass, especially a car window.

Commonly confused: fog or smog? fog or frog?

Practice

Make it your own

Write a sentence using “fog”, then check it and compare it with the examples above.

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