The complement system is a critical component of the body's immune response, responsible for targeting and eliminating invading pathogens. However, there are several synonyms for complement system, such as alternative pathway, classical pathway, and lectin pathway. The alternative pathway is activated by spontaneous hydrolysis of C3 and functions as a broad defense mechanism against pathogens. The classical pathway is triggered by antigen-antibody complexes and is critical for immune defense against bacteria and viruses. The lectin pathway is activated by patterns on the surface of foreign pathogens and can trigger inflammation and subsequent clearance of pathogens by phagocytes and other immune cells. Overall, understanding synonyms for complement system can help facilitate communication and collaboration among healthcare professionals in treating patients with immunological disorders.