/ ɪˈnɜːʃə; NAmE -ɜːrʃə/ noun [ U ]
1.
(usually disapproving ) lack of energy; lack of desire or ability to move or change :
I can't seem to throw off this feeling of inertia.
the forces of institutional inertia in the school system
2.
( physics ) a property (= characteristic) of matter (= a substance) by which it stays still or, if moving, continues moving in a straight line unless it is acted on by a force outside itself
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WORD ORIGIN
early 18th cent. (in sense 2): from Latin , from iners , inert- unskilled, inactive, from in- (expressing negation) + ars , art- skill, art.