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A·ver·no(ä-vĕr′nō) Ancient name A·ver·nus (ə-vûr′nəs)
A small crater lake of southern Italy near the Tyrrhenian Sea west of Naples. Because of its gloomy aspect and intense sulfuric vapors, now extinguished, the ancient Romans regarded it as the entrance to the underworld.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Placename) a crater lake in Italy, near Naples: in ancient times regarded as an entrance to hell. Latin name: Avernus
[from Latin, from Greek aornos without birds, from a-1 + ornis bird; referring to the legend that the lake's sulphurous exhalations killed birds]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014