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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.