noun
acid
A-sihd
noun
1
In chemistry, a substance that reacts with a base, tastes sour, and can turn litmus paper red; on the pH scale it measures below 7.
"Vinegar contains a mild acid called acetic acid."
"The chemist wore gloves while handling the strong acid."
2
Slang for LSD, a powerful hallucinogenic drug.
"He claimed the band wrote the album after dropping acid."
adjective
1
Sour or sharp-tasting, like vinegar.
"The wine had an acid tang that made her wince."
How to Use Acid
Learner’s notesIn plain EnglishA sour or corrosive chemical substance — or, informally, the drug LSD.
When to use it
The drug sense is informal slang, not used in medical or scientific writing.
Common pairings
stomach acid
acid rain
acid test
drop acid
Word Forms
acider comparative, acids plural, acidest superlative
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Vinegar contains a mild _____ called acetic acid.
Etymology
From French acide, from Latin acidus, "sour," related to the verb aceo, "to be sour."