foggy

foggy — adjective

1. so full of mist or low-hanging cloud that you cannot see clearly where you are o

1.adjectiveA2
Definition

so full of mist or low-hanging cloud that you cannot see clearly where you are or what is around you; also used for a glass or window surface that has steam on it, making it hard to see through

Example

The ferry stayed in port because the harbour was too foggy for safe sailing.

literal weather: foggy harbour/road/path

Linh wiped the foggy bathroom mirror with a towel so she could see her reflection.

steamed surface: foggy mirror/window/glass

Common collocations
  • foggy morning
  • foggy night
  • foggy weather
  • foggy mirror
  • foggy window
  • foggy windscreen
  • foggy road
  • foggy harbour
Synonyms
  • misty

    weaker than foggy; mist has smaller water droplets and slightly better visibility

  • hazy

    suggests a general lack of clarity in the air, not necessarily caused by fog; can also be from heat or smoke

  • cloudy

    used for the sky rather than ground-level air; a cloudy sky does not mean foggy ground conditions

Antonyms
  • clear

    no fog or mist; easy to see

  • sunny

    bright with sunshine, the opposite of foggy weather

Grammar Patterns

foggy + noun

linking verb + foggy

Common Mistakes

It is foggy to go outside today.
It is foggy outside today.
foggy is an adjective describing the weather, not a structure for permission or possibility.
The window is foggy because I forgot to clean it.
The window is foggy because of the steam from the hot shower.
when used for surfaces, foggy means covered with condensed water vapour, not simply dirty.

2. unable to think in a clear or quick way, often because you have not slept enough

2.adjectiveB1
Definition

unable to think in a clear or quick way, often because you have not slept enough, are sick, or have taken medicine that affects your concentration

Example

Ishaan felt so foggy after three hours that he could not follow the lecture.

feel + foggy (mental state from tiredness)

The cold medicine made Sivan foggy and drowsy, so she stayed home instead of driving.

make + [person] + foggy (external cause)

Common collocations
  • feel foggy
  • mind is foggy
  • head is foggy
  • woke up foggy
  • still foggy
Synonyms
  • groggy

    more specific to tiredness or weakness after waking up or being ill; less formal than foggy

  • dazed

    suggests shock or surprise rather than natural tiredness

  • muddled

    emphasises confused thinking rather than slowness; can be used for organised thoughts

Antonyms

Grammar Patterns

linking verb + foggy

feel + foggy

make + [person] + foggy

Usage Note

This sense describes a temporary state of reduced mental sharpness caused by external factors such as lack of sleep, illness, medication, or jet lag. It is almost always used in predicative position (e.g. 'I feel foggy,' 'My head is foggy') rather than before a noun. Distinguish from sense 3 (VAGUE MEMORY), which is about memory of past events or knowledge of a subject rather than current mental clarity.

Common Mistakes

I feel foggy about yesterday's meeting.
I am foggy about yesterday's meeting.
for a confused mental state (sense 2), 'feel foggy' is correct; but 'foggy about' followed by a topic shifts the meaning to sense 3 (hazy memory). Use 'feel foggy' without 'about' for mental confusion.

3. not able to remember past events or details clearly; having very little knowledg

3.adjectiveB1
Definition

not able to remember past events or details clearly; having very little knowledge about a particular subject

Example

I am foggy about what happened after the toast but recall the party's first hour.

pattern: foggy about + [event/details]

Joon was foggy on the lease terms and asked the landlord to explain each clause.

pattern: foggy on + [topic/subject]

Common collocations
  • foggy about the details
  • foggy on the facts
  • foggy in my memory
  • foggy about what happened
Synonyms
  • hazy

    very similar to foggy for this sense; hazy may suggest a less severe degree of unclearness

  • vague

    describes the quality of the memory itself ('a vague recollection') rather than a person's state

  • sketchy

    informal; suggests that only a rough outline of the facts is known

Antonyms
  • vivid

    very clear, bright, and detailed in memory

  • crystal-clear

    completely clear, as if just seen or experienced

Grammar Patterns

be + foggy + about + [topic]

be + foggy + on + [topic]

foggy + in + [possessive] + mind / memory

Usage Note

This sense is about the clarity of stored knowledge or memory. The fixed expression 'not have the foggiest (idea/notion)' is a common emphatic idiom meaning 'have absolutely no idea' — see Idioms below. Distinguish from sense 2 (CONFUSED MIND), which describes current mental function rather than knowledge recall.

Common Mistakes

I don't have the foggiest where my keys are.
I don't have the foggiest idea where my keys are.
the idiom requires 'idea' or 'notion' after 'foggiest'; dropping it is ungrammatical in standard English.

❌ 'I am foggy about the math problem because I did not sleep well.' — this mixes sense 3 (hazy about details) with sense 2 (tiredness). If the cause is tiredness, use sense 2 without 'about': 'I feel foggy because I did not sleep well.'

Idioms

not have the foggiest (idea / notion)

idiom

to have absolutely no knowledge or understanding of something — used to emphasise that someone knows nothing at all about a particular fact, event, or situation

The new student had never studied French literature, so she did not have the foggiest idea what the professor was discussing.

When the mechanic asked what sound the engine was making, Élise admitted she did not have the foggiest notion.

not have the foggiest (idea)

idiom

To have no knowledge or understanding about something.

Maya asked about the meeting time, but I didn't have the foggiest.

Does Brian have any clue where his keys are? He hasn't the foggiest idea.

Word family

  • fog
    nounA2
  • fog
    verbB1
  • fogginess
    nounC1
  • foggily
    adverbC1

Synonym discussion

Sense: adjective/1

All four words describe reduced visibility in the air, but they differ in cause and degree. Foggy is the strongest — visibility drops to under one kilometre, making it hard to see where you are going. Misty is lighter; mist has smaller water droplets and the air looks soft and grey, but you can still make out distant shapes. Hazy can come from heat, smoke, or pollution rather than water droplets, and it makes outlines look blurry rather than completely hiding objects. Cloudy refers only to the sky — a day can be cloudy with thick grey clouds above but perfectly clear air at ground level. For example, 'The mountain peak was foggy, so we could not see the trail,' but 'The peak was hazy from the summer heat,' and 'It was a cloudy day but clear enough for a long walk.'

foggy ↗misty ↗hazycloudy ↗

Common collocations

Nouns

  • foggy weather
  • foggy morning
  • foggy memory
  • foggy idea

Adverbs

  • very foggy
  • extremely foggy
  • quite foggy
  • terribly foggy
  • still foggy

Phrases

  • a foggy day
  • in a foggy state

Prepositions

  • foggy about
  • foggy on

Etymology

Germanic (Old Norse/Danish)English

Foggy comes from the noun 'fog' (thick mist near the ground) plus the suffix '-y' meaning 'full of'. The noun 'fog' probably entered English in the 1500s from Danish or Norwegian 'fog' (driving snow or spray). Before that, the usual word for thick mist was 'mist'. The figurative meanings ('confused in thought' and 'unclear in memory') appeared in the 1500s and 1600s, using the idea of fog as something that makes clear vision — and therefore clear thinking — impossible.