Added 9 October 2026 flu /fluː/ noun Categories: Describing WordsRare Words In Latin: influentia Wiktionary noun ! Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about flu at Wordnik → Where our words come from → An acute febrile highly contagious viral disease. Origin Clipping of influenza. From Wiktionary, via Kaikki.org (CC BY-SA) Related Words: grippeinfluenzaplagueviruspandemicvaccinationvaccinediseasecoldavianbirdflow Back to today's word