flat spot
n 1. (General Engineering) engineering a region of poor acceleration over a narrow range of throttle openings, caused by a weak mixture in the carburettor
2. (Mechanical Engineering) any narrow region of poor performance in a mechanical device
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014