The term "normal opsonin" refers to a substance in the body that enhances the ability of white blood cells to engulf and destroy bacteria. There are several synonyms for this term, including "opsonic agent," "opsonizing factor," and "opsonizing antibody." These substances play an important role in the immune system by helping to identify and eliminate harmful pathogens. However, if the levels of normal opsonin are too low, the body may become more vulnerable to bacterial infections. Therefore, identifying and maintaining a healthy level of normal opsonin is essential for maintaining good health and preventing serious infections.