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An insoluble white protein that is the essential component of raw silk and spider-web filaments.
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.
(Zoology) a tough elastic protein that is the principal component of spiders' webs and raw silk
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
fi•bro•in(ˈfaɪ broʊ ɪn)
an indigestible protein that is a principal component of spider webs and silk.
[1860–65; < French]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.