Where does “OSI” come from?

OSI (German) comes from English aussie, from English Australian, from English Australia, from Latin terra austrālis incōgnita, from Latin auster, from Proto-Italic *austeros.

Ancestry of “OSI”, step by step

Step	Language	Word	Meaning
1	English	aussie	—
2	English	Australian	A person from the country of Australia or of...
3	English	Australia	—
4	Latin	terra austrālis incōgnita	—
5	Latin	auster	The south wind; south
6	Proto-Italic	*austeros	—

Every word from Proto-Italic *austeros →