PFI, or Private Finance Initiative, is a term used to describe a UK government program for funding public infrastructure through private sector investment. However, there are several synonyms that can be used to describe this program. Some of the common synonyms for PFI include Public-Private Partnership (PPP), Private Sector Investment (PSI), and Build-Operate-Transfer (BOT). These terms are often used interchangeably to describe similar programs for public infrastructure funding through private investment. Other similar terms include Concession, which describes the granting of rights to operate and maintain public infrastructure to private companies, and Infrastructure Finance, which refers to all forms of financing for public infrastructure, including government bonds and private investment.