What is "caenophrurium"

Caenophrurium (also written as Cænophrurium, Cenophrurium and Coenophrurium; , Kainophrourion) was a settlement in the Roman province of Europa (the southeasternmost part of Thrace), between Byzantium and Heraclea Perinthus. It appears in late Roman and early Byzantine accounts. Caenophrurium translates as the "stronghold of the Caeni", a Thracian tribe.