A flat, pear-shaped drinking vessel with loops for attachment to the belt of the user.
[Middle English, from Old French costerel, possibly from costier, at the side, from coste, rib, from Latin costa; see kost- in Indo-European roots.]
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.
(Brewing) obsolete a flask, usually of earthenware or leather
[C14: from Old French costerel, from coste side, rib, from Latin costa]
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