acid
gb/ˈæsɪd/ us/ˈæsɪd/
A2
English
~ 1700
Senses
0 senses
Noun
B1
entity
1
Sour chemical compound
A sour-tasting substance in chemistry that can react with other substances.
Usage pattern:
[acid] reacts with [something]
Common mistake:
Learners sometimes confuse 'acid' with 'acidic', using 'acid' as an adjective incorrectly.
Synonyms
acidic substance (More descriptive term referring to the property of being acidic.)
Antonyms
base (A substance that can neutralize an acid and has a pH above 7.)
Collocations
strong acid
|weak acid
|acid solution
|acid rain
|acid level
Themes
science
|chemistry
|food
|core_vocabulary
Examples
- Lemon juice contains citric acid, which gives it its sour taste.
- The scientist measured the acidity of the acid solution.
- Vinegar is a weak acid commonly used in cooking.
- Acid rain can damage buildings and harm plants.
- Hydrochloric acid is used in many industrial processes.
Learner examples
- Lemon has acid in it.
- Vinegar is an acid.
- Acid can burn your skin.
- Acid and base can mix together.
adjective
A2
property
2
Sharp or sour-tasting
Tasting or smelling sharp and sour, like lemon or vinegar.
Usage pattern:
an acid [taste/smell]
Common mistake:
Learners may incorrectly use 'acid' instead of 'sour' in casual food contexts where 'sour' is more natural.
Synonyms
sour (Common taste descriptor; less technical than 'acid'.)
Antonyms
sweet (Opposite taste profile to sour/acidic.)
Collocations
acid flavor
|acid tang
|acid scent
Themes
food
|sensory
|food_drink
|core_vocabulary
Examples
- The wine had a slightly acid finish.
- She wrinkled her nose at the acid smell from the jar.
- This apple has a pleasantly acid flavor.
Learner examples
- The lemon has an acid taste.
- I do not like the acid smell.
- This fruit is very acid.
Noun
slang
B2
entity
3
Hallucinogenic drug LSD
A street name for the illegal drug LSD, which changes how people see and feel things.
Usage pattern:
take [acid]
Common mistake:
Learners may confuse this slang meaning with the scientific meaning of 'acid'. Context is crucial.
Synonyms
LSD (The chemical name; more formal/scientific than slang 'acid'.)
Collocations
drop acid
|take acid
|acid trip
Themes
drugs
|slang
|health
|daily_life
Examples
- He was arrested for possession of acid.
- She said she took acid at the concert and had vivid hallucinations.
- The movie tried to capture the feeling of an acid trip.
Learner examples
- He took acid at the party.
- Acid is not legal in my country.
- Some people use acid to feel strange.
adjective
B2
property
4
Harsh or cutting in tone
Using words that are very unkind or hurtful.
Usage pattern:
an acid [remark/comment]
Common mistake:
Learners may take this figurative meaning literally as related to taste or chemistry.
Synonyms
biting (Emphasizes sharpness and hurtfulness in tone; similar figurative use.)
Antonyms
kind (Opposite in tone; gentle or pleasant speech.)
Collocations
acid remark
|acid wit
|acid tongue
Themes
communication
|emotions
|core_vocabulary
Examples
- Her review was full of acid remarks about the acting.
- He gave me an acid look when I interrupted him.
- The debate turned personal, with several acid comments exchanged.
Learner examples
- She made an acid comment about my clothes.
- He spoke with an acid voice.
- The teacher gave an acid reply.
Grammar
Dictionary form
acid
IPA
GB/ˈæsɪd/
US/ˈæsɪd/
Syllables & stress
acid (1 syllable)
Stress on 1st syllable (acid)
Word forms
Adjective
- Base: acid
Noun
- Base: acid
- Plural: acid, acids
Word family
Forms
acids
noun
Core family
acidic
adjective B1
acidity
noun
Related words
antacid
noun
acidify
verb
Negative and opposite forms
alkaline
adjective
Advanced or less common
acidification
noun
Expressions
acid rain
1/ˈæsɪd ɹˈeɪn/
fixed phrase
technical
Rain with acidic pollutants
Rain that has harmful chemicals from pollution and can damage nature and buildings.
Examples
- Acid rain has destroyed many forests in the region.
- Scientists are studying ways to reduce acid rain caused by factories.
acid test
1/ˈæsɪd tˈɛst/
idiom
Decisive proof of quality
A final and most important test to show if something is good or works well.
Examples
- The new software faces its acid test when it is released to the public.
- Playing against the top team will be the acid test for our defense.
drop acid
1/dɹˈɑp ˈæsɪd/
fixed phrase
slang
Take LSD drug recreationally
To take the illegal drug LSD to experience its effects.
Examples
- They dropped acid before going to the music festival.
- He said he once dropped acid in college but never again.