complement factor

This term is a specialized medical and biochemical designation used primarily in immunology and hematology. It refers to the specific proteins that act as a cascade to "complement" the ability of antibodies and phagocytic cells to clear pathogens from an organism. Because it describes a specific biological component, it is used almost exclusively in clinical reports, academic research, and diagnostic contexts.

In a clinical setting, the term is often followed by a letter (e.g., complement factor B, C3, or C4) to specify which protein in the complement system is being discussed. Misuse of this term in general conversation would be perceived as overly technical or jargon-heavy, as it describes a microscopic molecular process rather than a general health state.