What is Bill Of Sufferance?

Legal Definition
In English law. A license granted at the custom-house to a merchant, to suffer him to trade from one English port to another, without paying custom. Co.well. 12. In criminal law, a bili of indictment, see infra.
-- Black's Law Dictionary
Legal Definition
A license exempting from duty a merchant trading between English ports.
-- Ballentine's Law Dictionary