ecoregion (?i?k???ri?d??n) n (Physical Geography) an area defined by its environmental conditions, esp climate, landforms, and soil characteristicsCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014