Green’s Dictionary of Slang

(Aus.) an image of great distance.

1903

Bulletin (Sydney) 12 Nov. 16/4: Out-Back, Wayback, Rightback, Back-o’-Out-Back, Beyond-Out-Back, Behind-Out-Back, Set-o’-Sun, Death-o’-Day, Past-West, Westest-West, Beyond-Set-o’-Sun, Right-Behind-Death-o’-Day, and so on.