Neck and shoulder mail that is attached to a helmet.
[Middle English aventaille, aventail, beaver of a helmet, from Anglo-Norman, probably alteration of esventail, aventail, from Old French esventer, to let out air, ventilate, from Vulgar Latin *exventāre; see VENT1.]
(click for a larger image)aventail
c. 1390-1410 basinet helmet with aventail
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
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