- Lack of activity or exertion; habitual indisposition to action or motion
- Absence of the power of self-motion; inertia.
- (chemistry) Quality of being unreactive with other chemical compounds or elements.
- inertness in The Century Dictionary, The Century Co., New York, 1911
- inertness in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913