What does "clean bill of health" mean?

A report confirming the absence of fault or guilt in a person or thing, as in Jeff checked every component and gave the computer a clean bill of health, or He had a foolproof alibi so the police had to give him a clean bill of health. This term comes from a 17th-century practice of requiring ships to produce a medical document (bill) attesting to the absence of infectious disease on board before landing.