Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “acid”

acid

noun uk   /ˈæs.ɪd/ us  

acid noun (CHEMICAL)

B2 [C or U] any of various usually liquid substances that can react with and sometimes dissolve other materials: acetic/hydrochloric/lactic acid Vinegar is an acid.

acid noun (DRUG)

[U] slang for LSD (= an illegal drug that makes people see things that do not exist)

acid

adjective uk   /ˈæs.ɪd/ us  

acid adjective (CHEMICAL)

(also acidic) containing acid, or having similar qualities to an acid: an acid taste/smell acid soil

acid adjective (UNKIND)

describes a remark or way of speaking that is cruel or criticizes something in an unkind way: her acid wit When she spoke her tone was acid.
(Definition of acid from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of acid?
Browse related topics

You are looking at an entry to do with Specific types of drug, but you might be interested in these topics from the Drugs topic area:

Add Cambridge dictionaries to your browser to your website

Definitions of “acid” in other dictionaries

Word of the Day

monster

any imaginary frightening creature, especially one that is large and strange

Word of the Day

What’s that lovely smell?

by Kate Woodford,
October 29, 2014
As adult humans, we can distinguish about 10,000 different smells. It’s no wonder, then, that we have so many words and expressions to describe them. This week we’re taking a look at those smell words – words that describe good smells and words that describe bad smells. Most smell words are either

Read More 

high-frequency trading noun

October 27, 2014
a type of stock market trading that uses very complex technology to trade extremely quickly, often making tiny profits which nevertheless add up to substantial sums Lewis’s book, Flash Boys, is driving a huge amount of attention toward the topic of high frequency trading, and it has rekindled some of

Read More