What does "PI" mean in Australia? In the United States a "PI" is a principal investigator.  This is someone who leads grant applications.  What does "PI" mean in Australia?
In Australia, "PI" means partner investigator.  This is someone who is involved in a grant application but is not eligible for funding.  For example, they might be an international collaborator.

A grant applicant is a "Chief Investigator" or "CI."

Reference:  http://www.arc.gov.au/eligibility-matters