The term 'chemically unreactive' is often used to describe a substance that does not react with other substances when exposed to them. This term is also known as 'INERT', which is a five-letter word that can be found in crossword puzzles. INERT substances are usually gases, such as nitrogen, or solids, such as carbon dioxide, that do not react with other substances when exposed to them. These substances are important in many industrial processes, as they can be used to prevent unwanted reactions from occurring.