Main Entry: in·flu·en·za

Pronunciation: \ˌin-(ˌ)flü-ˈen-zə\

Function: noun

Etymology: Italian, literally, influence, from Medieval Latin influentia; from the belief that epidemics were due to the influence of the stars

Date: 1743

1 a (1) : an acute typically severe respiratory disease caused by an orthomyxovirus (species Influenza A virus of the genus Influenzavirus A) and marked by sudden onset, fever, prostration, severe aches and pains, and progressive inflammation of the respiratory mucous membranes—called also influenza A (2) : either of two usually milder or even subclinical respiratory diseases caused by two other orthomyxoviruses (species Influenza B virus of the genus Influenzavirus B and species Influenza C virus of the genus Influenzavirus C) —often used with the letter B or C to denote the causative species b : any of various human respiratory infections of undetermined cause —not used technically
2 : any of numerous febrile usually virus diseases of domestic animals marked by respiratory symptoms, inflammation of mucous membranes, and often systemic involvement

— in·flu·en·zal \-zəl\ adjective