Technical Abstract: Accurate definition and usage of terminology are critical to effective communication in science. In a recently published article, the clarity and consistency of the terms pathogenicity and virulence in invertebrate pathology were called into question, and a revision of these terms was proposed. Our objective was to examine definitions and usage of pathogenicity and virulence in invertebrate pathology, and respond to this previously published article on the subject. Although the usage of the terms pathogenicity and virulence varies in the invertebrate pathology literature, we found considerable constancy in invertebrate pathology textual definitions of these terms throughout the history of the discipline and among related disciplines such as medicine and microbiology. We did not find the established definitions to be lacking in clarity or utility. Therefore, we recommend invertebrate pathology definitions adhere to precedence and remain as follows: pathogenicity is quality or state of being pathogenic, the potential ability to produce disease. Virulence is the disease producing power of an organism, the degree of pathogenicity within a group or species.