oner (?w?n?) n1. a single continuous action (esp in the phrase down it in a oner)2. an outstanding person or thing3. a heavy blow[C20: from one]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014