Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018British Dictionary definitions for sui generis
Latin, literally: of its own kind
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for sui generis
1787, Latin, literally "of one's own kind, peculiar." First element from sui, genitive of suus "his, her, its, one's," from Old Latin sovos, from PIE root *swe-, pronoun of the third person (see idiom).
Online Etymology Dictionary, © 2010 Douglas Harper
[(sooh-ee, sooh-eye jen-uh-ris)]
A person or thing that is unique, in a class by itself: “She is an original artist; each of her paintings is sui generis.” From Latin, meaning “of its own kind.”
The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.