influenza

This term refers specifically to the viral infection of the respiratory system. While often used interchangeably with the casual term flu, influenza in a medical context denotes a specific group of viruses that cause seasonal epidemics and occasional pandemics. As an uncountable noun, it describes the disease as a general condition. When referring to specific instances or types of the virus, it remains uncountable unless modified by a partitive or used in a technical classification of strains.