Pronunciation: (in-ûr'shu, i-nûr'-),[key] —n. 1. inertness, esp. with regard to effort, motion, action, and the like; inactivity; sluggishness.
2. Physics. a. the property of matter by which it retains its state of rest or its velocity along a straight line so long as it is not acted upon by an external force.
b. an analogous property of a force: electric inertia. 3. Med.lack of activity, esp. as applied to a uterus during childbirth when its contractions have decreased or stopped.