cachexia UK /kəˈkɛksɪə/US /kəˈkɛksiə/ noun1 •A systemic wasting of muscle tissue, with or without loss of fat mass, that accompanies a chronic disease.Cancer cachexia is a complex metabolic process, due to both host and tumor factors, which results in excess catabolism as well as aberrant fat and carbohydrate metabolism. — 2007 formscachexiae · cachexias