acid
/ˈæsɪd/adjective, noun
acid is spelled A-C-I-D: 4 letters and 2 syllables. It appears 28 times per million words in written English, the 3,288th most frequent word form (wordfreq, 2021 data). As an adjective, acid means “Sour, sharp, or biting to the taste; tart; having the taste of vinegar” (English Wiktionary, September 2026).
How many letters and syllables are in acid?
| Letters | 4: A-C-I-D |
|---|---|
| Syllables | 2 (from its American pronunciation) |
| In writing | 28 times per million words; the 3,288th most frequent word form |
| Wrong spellings searched | none measured in search |
| Same letters |
Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media); rhymes and same-letter words are computed by PlainSpell from its own word list.
How common is acid?
Acid appears 28 times per million words in written English, the 3,288th most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How do you pronounce acid?
- US /ˈæsɪd/
Acid has 2 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Naomi_Persephone_Amethyst_(NaomiAmethyst)-acid.wav, En-us-acid.ogg, Wikimedia Commons (author and licence on each file's page).
What rhymes with acid?
No other word on PlainSpell ends in the same sounds as acid (/æsɪd/).
Spelled with the same letters in another order: adic, cadi, caid.
Computed by PlainSpell from the pronunciations in the English Wiktionary (dump of September 2, 2026): a rhyme shares every sound from the last stressed vowel to the end; ordered by written frequency (wordfreq 3.1).
Forms of acid
- acider comparative
- acidest superlative
- acids plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
What does acid mean?
The meanings the English Wiktionary records, quoted as written there (source below).
adjective
- 1
Sour, sharp, or biting to the taste; tart; having the taste of vinegar.
acid fruits or liquors
- 2
Sour-tempered.
His response was harsh and acid.
- 3
Of or pertaining to an acid; acidic.
acid soils
- 4
Denoting a musical genre that is a distortion (as if hallucinogenic) of an existing genre, as in acid house, acid jazz, acid rock.
noun
- 1
A sour substance.
- 2
Any compound which yields H+ ions (protons) when dissolved in water; an Arrhenius acid.
- 3
Any compound that easily donates protons to a base; a Brønsted acid.
- 4
Any compound that can accept a pair of electrons to form a covalent bond; a Lewis acid.
- 5
Any corrosive substance.
- 6
slangLSD, lysergic acid diethylamide.
noun
- 1
Acronym of atomicity, consistency, isolation, and durability, a set of properties that guarantee database transactions are processed reliably.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
Acid in Spanish, French, German and Portuguese
| Language | Words |
|---|---|
| French | aigre, acide |
| German | sauer , Säure |
| Portuguese | ácido, azedo |
| Spanish | agrio, ácido , malhumorado |
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.
Where does acid come from?
From French acide, from Latin acidus (“sour, acid”), from aceō (“to be sour”). Doublet of agita.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).