The term 'THEY MAY BE COVERED' can be solved by the word 'BASES', which is a five-letter word. Bases are a type of chemical compound that are composed of positively charged ions called cations and negatively charged ions called anions. They are important in many areas of chemistry, including biochemistry, as they are involved in many biochemical reactions. Bases are also used to describe the pH of a solution, with higher pH values indicating a more basic solution.