[in.er.tia] n [NL, fr. L, lack of skill, fr. inert-, iners] (1713) 1 a: a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force b: an analogous property of other physical quantities (as electricity)
2: indisposition to motion, exertion, or change: inertness -- in.er.tial adj -- in.er.tial.ly adv