for week of April 17, 2006:
Pack-off 1. (noun) A device that allows a cable or wireline to be hydraulically sealed off so that a drill pipe or tubing string can be pressurized while wireline tools are in place within the pipe or tubing string.
2. (verb) To create a hydraulic or mechanical seal between a wireline, cable, or tubing string while it is within a larger pipe or tubing string, to allow the larger pipe to be pressurized.