Increasing coupling used on hose, pump, or nozzles to permit connection of a larger size of hose.
A fitting used to enlarge a vent stack as it passes through the roof. Home Improvement Encyclopedia
Plumbing drainage fitting that enlarges the diameter of a straight-line run by virtue of its larger size on one end and smaller on the other. If it is used for the reverse, to make the diameter of a straight-line run smaller, it is called a reducer.