mnemosynum

From Ancient Greek μνημόσυνον (mnēmósunon), from μνημοσύνη (mnēmosúnē, “memory”).

mnēmosynum n (genitive mnēmosynī); second declension (hapax legomenon)

1. a keepsake, souvenir, or memorial
   • c. 84 BCE – 54 BCE, Catullus, Carmina 12.13:

     verum est mnemosynum mei sodalis.

     but because it is a souvenir of my drinking buddy.

Second-declension noun (neuter).

• “mnemosynum”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• "mnemosynum", in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• mnemosynum in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• mnemosynum in Ramminger, Johann (16 July 2016 (last accessed)) Neulateinische Wortliste: Ein Wörterbuch des Lateinischen von Petrarca bis 1700‎^[1], pre-publication website, 2005-2016