PR is the medical term for Per Rectal Examination, where the doctor sticks his finger up a patient's anus to look for signs for rectal cancer. The term has long been in use before Google hijacked it but this time round, Google has really stuck a finger or rammed a fist up many webmasters' arses.!
PR is just an abbreviation. Although doctors use it, Page Rank(PR) is named after an actual person, Larry Page.
PR is nothing donot bother about that work constantly & according to ur SEO Strategies, You found have a good amount of PR on ur website.