We don't have synonyms for brumby yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are crumby, brummy and bumby.
"1988: Harry Farquharson said there were two or three springs and that the horses were "bloody wild". He said there were probably about 300 and they were good horses, a long way above the average brumby. -- Tom Cole, Hell West and Crooked"
"1988: Harry Farquharson said there were two or three springs and that the horses were "bloody wild". He said there were probably about 300 and they were good horses, a long way above the average brumby. -- Tom Cole, Hell West and Crooked"