A-sample n (General Sporting Terms) the primary urine or blood sample used in doping tests in professional sports; if the A-sample tests positive, the B-sample is tested to confirm or invalidate the results. See also B-sample Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014