Englishfor English speakers
acid
Noun
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An acid is a liquid with a high number of hydrogen ions in it that can burn things.
Fruit often has a little acid in it.
The acid burned the table.
Acids taste sour but bases taste bitter.
acid
Adjective
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If something is acid, it is like an acid, from an acid, or acidic.
The factories nearby have made the lake more acid.
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If something has an acid taste, it is sour.
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If something said or done to you was acid, it was hurtful.
Their acid comments are painful.
catalyst
Noun
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A substance that makes a chemical reaction happen faster. The catalyst is not changed by the process and can be used again.
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A catalytic converter.
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Someone or something that encourages progress or change, or helps it happen.
I hope the new CEO will be a catalyst for change.
Communication is a catalyst for peace.