Lactam is a chemical compound that contains a cyclic amide functional group. There are several synonyms for this compound, including azetidinone, pyrrolidone, and oxazolidone. These terms are often used interchangeably depending on the specific chemical structure and application. Azetidinone is commonly used in the pharmaceutical industry as a building block for the synthesis of drugs such as zileuton and valdecoxib. Pyrrolidone is used in the production of polymers, solvents, and as a starting material for the synthesis of agrochemicals. Oxazolidone is also used in the pharmaceutical industry as an antifungal agent. Despite their differences, these synonyms are all related to the same chemical group and play important roles in a variety of fields.