I've never heard the term, but I would guess that it may involve putting a rod (dowel) into a hole that is designed to prevent the equipment from turning.
It is a process where a piece of rotating equipment is fixed to its base once it is fully aligned. This is over and above the use of anchor bolts. It is not always done and some believe it is an unnecessary step in equipment alignment. Typically a hole is drilled through the equipment and the base. The hole is tapered and a tapered rod or dowel is driven into the hole. With two dowels, a pump or compressor can be held so it will not slide around and if moved can be put back in the exact place it should be.
Dowels are meant to locate, fasteners only fasten.
