What does -stae mean in Latin?

-stae, a suffix, means “Found in Illyrian ethnonyms formed from toponyms.”.

suffix · femininefirst declension

-stae

-stae f pl (genitive -stārum)

femininemorphemepluralFound in Illyrian ethnonyms formed from toponyms.
Burnum + -stae → Burnistae
Splonum + -stae → Splonistae

Borrowed from Illyrian. Compare also -stinī, -tae, -tēs.

What does -stae mean in Latin?: -stae, a suffix, means “Found in Illyrian ethnonyms formed from toponyms.”.