1. An acute contagious viral infection of humans, characterized by inflammation of the respiratory tract and by fever, chills, muscular pain, and prostration. Also called grippe.
2. Any of various viral infections of domestic or wild animals, generally characterized by fever and respiratory involvement.
[Italian, from Medieval Latin īnfluentia, influence (so called apparently from the belief that epidemics were due to the influence of the stars); see INFLUENCE.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.