mechanism
noun
mech·a·nism
ˈme-kə-ˌni-zəm 
1
a
: a piece of machinery (see machinery sense 1)
The camera's shutter mechanism is broken.
b
: a process, technique, or system for achieving a result
the mechanisms of peace—
F. D. Roosevelt
F. D. Roosevelt2
: mechanical operation or action : working sense 2
he acknowledges nothing besides matter and motion; so that all must be performed either by mechanism or by accident—Richard Bentley
Richard Bentley3
: a doctrine that holds natural processes (as of life) to be mechanically determined and capable of complete explanation by the laws of physics and chemistry
4
: the fundamental processes involved in or responsible for an action, reaction, or other natural phenomenon
meteorologists believe that this pressure jump is the mechanism responsible for storms and tornadoes—Think
compare defense mechanism
ThinkExamples of mechanism in a Sentence
The camera's shutter mechanism is broken.
Scientists are studying the body's mechanisms for controlling weight.
There is no mechanism in place for enforcing the new law.
a legal mechanism to prevent lobbyists from exerting unfair influence
psychological mechanisms for dealing with a tragic loss
Recent Examples on the Web
Following the airspace violation, Estonia also has requested NATO Article 4 consultations, the mechanism which allows any member to formally bring an issue to the attention to the alliance’s principle political decision-making body.
—Nina Subkhanberdina, CNN Money, 21 Sep. 2025
These devices are decades old, and their internal mechanisms are often unstable.
—Sujita Sinha, Interesting Engineering, 21 Sep. 2025
The extra bacteria didn’t explain increases in vitamin D, though, which suggested that magnesium works on vitamin D metabolism both directly and through the microbiome, but via separate mechanisms.
—New Atlas, 21 Sep. 2025
The novel mechanism allows the wearer to take control over the automatic movement’s winding, adjusting the winding activity to their current level of activity.
—Rachel Cormack, Robb Report, 20 Sep. 2025
See All Example Sentences for mechanism
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Nina Subkhanberdina, CNN Money, 21 Sep. 2025
These devices are decades old, and their internal mechanisms are often unstable.
—Sujita Sinha, Interesting Engineering, 21 Sep. 2025
The extra bacteria didn’t explain increases in vitamin D, though, which suggested that magnesium works on vitamin D metabolism both directly and through the microbiome, but via separate mechanisms.
—New Atlas, 21 Sep. 2025
The novel mechanism allows the wearer to take control over the automatic movement’s winding, adjusting the winding activity to their current level of activity.
—Rachel Cormack, Robb Report, 20 Sep. 2025
See All Example Sentences for mechanism
Cite this Entry
“Mechanism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mechanism. Accessed 25 Sep. 2025.
Copy CitationKids Definition
mechanism
noun
mech·a·nism
ˈmek-ə-ˌniz-əm
1
: a piece of machinery
2
a
: the parts by which a machine operates
b
: the process, way, or system for achieving a goal
the mechanism of government
3
: the processes involved in or responsible for a natural occurrence (as evolution or an action or reaction)
Medical Definition
mechanism
noun
mech·a·nism
ˈmek-ə-ˌniz-əm
1
: a piece of machinery
2
a
: a bodily process or function
the mechanism of healing
b
: the combination of mental processes by which a result is obtained
psychological mechanisms
3
: the fundamental physical or chemical processes involved in or responsible for an action, reaction, or other natural phenomenon
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