An Inertia

(physics, uncountable or countable) The property of a body that resists any change to its uniform motion; equivalent to its mass. https://en.wikipedia.org/wiki/Inertia
(figuratively) In a person, unwillingness to take action.
(medicine) Lack of activity; sluggishness; said especially of the uterus, when, in labour, its contractions have nearly or wholly ceased.