As used in this Part, the term public retirement system shall mean this system, the New York State and Local Employees' Retirement System, the New York State and Local Police and Fire Retirement System, the New York City Employees' Retirement System, the New York City Teachers’ Retirement System, the New York City Board of Education Retirement System, the New York City Police Pension Fund, or the New York City Fire Department Pension Fund, unless the context otherwise requires a different meaning.