an imitation of the regular
sound made by a smoothly
running internal combustion engine.
—SHSBC Binder 2, 14, 17, 18, 19, 20, 21, 24, 26, 27, 28, 29, 30, 31, 32, 33 Approved Glossary, —Track Analysis and Running the GPMs Approved Glossary, —PDC Volume 1 Approved Glossary, —PDC 2 Approved Glossary, —PDC Volume 5 Approved Glossary, —NVRD Approved Glossary, —Grad V Approved 1992 Glossary Upgrade