any of various usually liquid substances that can react with and sometimes dissolve other materials

acetic/hydrochloric/lactic acid 醋酸／盐酸／乳酸

Vinegar is an acid. 醋是一种酸。

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

containing acid, or having similar qualities to an acid

an acid taste/smell 酸的味道／气味

acid soil 酸性土壤

used to describe a remark or way of speaking that is cruel or criticizes something in an unkind way

her acid wit 她的尖酸谐谑

When she spoke her tone was acid. 她说话时，语气尖酸刻薄。