These pages comprise a dictionary of terms relating to the pipe organ. Please keep definitions to a few sentences, and do not include pictures or sound clips. When more space is needed for a term, a new page can be created for it. Radiating [adj.] a term used to describe a pedalboard whose pedals are not parallel, but whose inner ends are splayed slightly further apart from each other than the outer ends. Radiating pedalboards are often (but not always) also concave. Ratio Reed Puller Reed Wire Register Regulation Reproducing Organ Reservoir Rib Rocker Rohrwerk [noun] reed stops. Roller Roller Arm Run