acid
noun · adjective
Simple meaning
a chemical that tastes sour, turns paper red, and reacts with bases
Pronunciation
Say it like this:
asuhdSay the bold part a little louder.
IPA pronunciation (US)
ˈæsəd
This word is pronounced essentially the same in American and British English, so one transcription covers both.
IPA (International Phonetic Alphabet) is a standard way of writing speech sounds.
Definition
Everyday modern meanings first, grouped by part of speech.
noun
chemistry
Any compound which yields H+ ions (protons) when dissolved in water; an Arrhenius acid.
chemistry
Any compound that easily donates protons to a base; a Brønsted acid.
chemistry
Any compound that can accept a pair of electrons to form a covalent bond; a Lewis acid.
Any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt
A sour substance.
Any corrosive substance.
adjective
Sour, sharp, or biting to the taste; tart; having the taste of vinegar.
figuratively
Sour-tempered.
Word at a Glance
- Difficulty
- A1 · Beginner (estimated)
- Frequency
- Common
- Typical Use
- General English
Word Aura™
How this word commonly comes across.
Aura for this meaning
This meaning: Any compound which yields H+ ions (protons) when dissolved in water; an Arrhenius acid.
For native speakers, 'acid' often brings to mind sour tastes (like lemon), corrosive properties, or specific chemicals like 'stomach acid' or 'battery acid.' It's a common term in both everyday language and scientific contexts, often contrasted with 'base' or 'alkaline.'
- Emotional tone
- Neutral
- Formality
- Specialist/technical
- Intensity
- Not strongly marked
- How common
- Specialized
- Connotation
- Clinical and technical
- Usage feel
- Technical and specialized
Where you'll really hear it
Science class
“Lemon juice is an acid because it tastes sour.”
Household safety
“Be careful; battery fluid is a strong acid.”
Food/Cooking
“Too much acid can make the sauce taste bitter.”
Where it naturally appears
- Science
- Academic writing
- Technical/specialist writing
Usage note
In general conversation this sense usually needs explaining — outside its field, people reach for a plainer word.
Word Aura describes common impressions, not a measurement. Tone changes with sentence, speaker, relationship and situation.
More ways to use acid
- “Lemons taste sour because they contain citric acid, which is a natural acid.”noun
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Common Patterns and Combinations
How this word naturally appears with others.
Word Family
Related forms, grouped by how they connect.
Word family
Words built from the same root.
The property of being acidic.
Related to Any compound which yields H+ ions (protons) when dissolved in water.
Compound terms
Established multiword terms.
A hydrogen atom in an acid that forms a positive ion when the acid dissociates.
Thriving in a relatively acidic environment (especially of plants requiring a pH well below 7).
Rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water.
Rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water.
A musical style that emerged in the 1960s.
A rigorous or crucial appraisal.
Related words
Connected by subject or meaning, not by word formation.
A hydrogen atom in an acid that forms a positive ion when the acid dissociates.
More about this wordSynonyms, forms, origin
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Dictionary data from Wiktionary via the Free Dictionary API. Simple meanings, combinations and word intelligence are built from verified reference data, no AI is used to load this page.