Thracum
Thracum is a Latin form of Thrax, meaning “Thracian; (Thraex) a type of gladiator”. It is the genitive plural masculine adjective or genitive plural feminine adjective.
Found 43 times in the Latin texts on Socratos.
Where it is used
Ovid, Metamorphoses 10.83: Ille etiam Thracum populis fuit auctor amorem
All forms of Thrax (declension table)
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Lewis & Short, A Latin Dictionary (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.