1. (physics) the mass of a body as determined by the second law of motion from the acceleration of the body when it is subjected to a force that is not due to gravity;
WordNet (r) 3.0 (2006):
inertial mass
n 1: (physics) the mass of a body as determined by the second
law of motion from the acceleration of the body when it is
subjected to a force that is not due to gravity