The term 'Australia Horse' is composed of four crossword solutions: Adelaide (8 letters), EMU (3 letters), Perth (5 letters), and OPAL (4 letters). Adelaide is the capital city of South Australia, located on the Adelaide Plains between the Gulf St Vincent and the low-lying Mount Lofty Ranges. The EMU is the largest bird native to Australia, and the second-largest in the world after the ostrich. Perth is the capital and largest city of Western Australia, located on the banks of the Swan River. Lastly, OPAL is a precious gemstone found in Australia, which is known for its unique play of color.