I call my horse Lilly "Brumby" as a term of endearment. But I didn't make the word up! In Australia a wild horse is called a brumby or brumbie. The word derives from the name of a Major William Brumby, an early 19th century settler from England who was a noted breeder of horses. Through the years a large number of his stock escaped and became feral. Another possible origin of the word-Booramby, Aborigine for wild.