influenza

Concise Oxford English Dictionary © 2008 Oxford University Press:
influenza/ɪnfluˈenzə/

▶noun a highly contagious viral infection of the respiratory passages causing fever, severe aching, and catarrh.

– derivatives
influenzal adjective.

word history: The words influenza, influence, and influx are closely linked, all deriving ultimately from Latin influere ‘flow into’. Influence originally referred to a supposed emanation from the stars, believed to affect human character and destiny; the notion of astral power was then transferred to personal power. The Italian word for influence, influenza, embraced the various senses of its English counterpart, but in addition, from the notion that the stars had an influence on health, took on the sense ‘an outbreak of an epidemic’. In 1743 it was applied specifically to an epidemic of flu that spread from Italy throughout Europe, and at this time the word influenza was adopted into English.