plural acids
1
chemistry
: a chemical with a sour taste that forms a salt when mixed with a base
the acids in your stomach
the kinds of acid found in your stomach
Note: An acid has a pH of less than 7. Very strong acids are able to burn holes in things.
2
slang
: lsd
His friend dropped acid [=took LSD] at the concert.
1
always used before a noun
: of, relating to, or having the qualities of an acid
He washes his windows with an acid solution of vinegar and water.
an acid [=sour] taste
This kind of plant grows well in acid [=acidic] soil.
Their pizza gives me acid indigestion. [=a burning feeling in the stomach]
2
: sharp, strong, and critical in tone
He made some very acid [=biting, caustic] comments.
acid remarks
Cite this Entry
“Acid.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/acid. Accessed 15 Apr. 2026.
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