acid rain acid radical • acid reaction · · · Info · Definitions · Synonyms · Characters · · acid rain · · Text Common · · Latin · · Scripts 9 · · Length 3 · · Syllables Definitions · · · (noun) rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water. Synonyms: acid rain, acid precipitation. · · Noun Definition 1 Synonyms · · · acid precipitation · · Synonym 1 Characters · · space U+0020 a latin small letter a U+0061 c latin small letter c U+0063 d latin small letter d U+0064 i latin small letter i U+0069 n latin small letter n U+006E r latin small letter r U+0072