tri·chloroacetic acid \(|)trī+-\noun alsotri·chloracetic acid\“+-\ Etymology: International Scientific Vocabulary trichlor- + acetic : a strong vesicant pungent deliquescent crystalline acid CCl3COOH made usually by chlorinating acetic acid or by oxidizing chloral and used in medicine as a caustic and astringent and especially in the form of salts in weed control — abbr. TCA