inertia
noun
in·er·tia
i-ˈnər-shə 
-shē-ə
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 (such as electricity)
2
: indisposition to motion, exertion, or change : inertness
overcame her inertia and finally changed jobs
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Inertia is the inherent property of a body that makes it oppose any force that would cause a change in its motion. A body at rest and a body in motion both oppose forces that might cause acceleration. The inertia of a body can be measured by its mass, which governs its resistance to the action of a force, or by its moment of inertia about a specified axis, which measures its resistance to the action of a torque about the same axis.
Examples of inertia in a Sentence
He blames governmental inertia for the holdup.
After 10 years in an unsatisfying job she overcame her inertia and went back to school.
Recent Examples on the Web
In a field defined by bureaucratic inertia, moving from contract to flight in under a year is nothing short of a developmental miracle.
—
Mrigakshi Dixit, Interesting Engineering, 13 Mar. 2026
The only thing that could work against it at this point is inertia—and enthusiasm for Sinners, a smash hit that picked up the most Oscar nominations this year and seems to engender a similar amount of love in the room at every industry event.
—David Sims, The Atlantic, 13 Mar. 2026
The Mini seems to change direction with almost no sense of inertia, biting into corners with terrier-like tenacity.
—Tim Pitt, Robb Report, 10 Mar. 2026
To exist at all is to feel the clock-steady undertow of inertia.
—Literary Hub, 9 Mar. 2026
See All Example Sentences for inertia
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Mrigakshi Dixit, Interesting Engineering, 13 Mar. 2026
The only thing that could work against it at this point is inertia—and enthusiasm for Sinners, a smash hit that picked up the most Oscar nominations this year and seems to engender a similar amount of love in the room at every industry event.
—David Sims, The Atlantic, 13 Mar. 2026
The Mini seems to change direction with almost no sense of inertia, biting into corners with terrier-like tenacity.
—Tim Pitt, Robb Report, 10 Mar. 2026
To exist at all is to feel the clock-steady undertow of inertia.
—Literary Hub, 9 Mar. 2026
See All Example Sentences for inertia
Cite this Entry
“Inertia.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/inertia. Accessed 17 Mar. 2026.
Copy CitationKids Definition
inertia
noun
in·er·tia
in-ˈər-shə
-shē-ə
1
: a property of matter by which it remains at rest or in unchanging motion unless acted on by some external force
2
: a tendency not to move or change
Medical Definition
inertia
noun
in·er·tia
in-ˈər-shə, -shē-ə
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
: lack of activity or movement
—used especially of the uterus in labor when its contractions are weak or irregular
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