CU' The term 'CU' is an abbreviation for the element COPPER, which is a chemical element with the symbol Cu and atomic number 29. COPPER is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. It is found in nature in its native form as well as in compounds. COPPER has been used by humans since ancient times and is still widely used today in many industries, such as electrical wiring, plumbing, and electronics.