Not attested: a series of unattested quotations. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "unattested" in a sentence
"There has literally been no point since 1400 when singular they went unattested in contemporary English."
"We could assume eg. a parallel but unattested Aegean loan to Anatolian from the same root, but that would remain speculation just as much."
"Further down history we may lack a suitable resolution of data — intermediate forms may go unattested — so some apparent disrepancies will be popping up."