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 …—
Franklin D. Roosevelt
Franklin 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
The deal with the government gives MP confidence to progress with expansions because China’s price-dumping threats are largely removed courtesy of the floor-pricing mechanism.
—Jordan Blum, Fortune, 17 Nov. 2025
To understand how ferric iron forms on the moon, the researchers examined several possible mechanisms and ruled out some alternatives.
—Bojan Stojkovski, Interesting Engineering, 16 Nov. 2025
Meanwhile, others are calling for mechanisms to help pursue college scholarships and study abroad, rather than going back online to study.
—Kareem El Damanhoury, CNN Money, 15 Nov. 2025
This acid is created by gut bacteria as a protective mechanism and previous research from the team has shown it to extend the life of roundworms and fruit flies.
—New Atlas, 14 Nov. 2025
See All Example Sentences for mechanism
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Jordan Blum, Fortune, 17 Nov. 2025
To understand how ferric iron forms on the moon, the researchers examined several possible mechanisms and ruled out some alternatives.
—Bojan Stojkovski, Interesting Engineering, 16 Nov. 2025
Meanwhile, others are calling for mechanisms to help pursue college scholarships and study abroad, rather than going back online to study.
—Kareem El Damanhoury, CNN Money, 15 Nov. 2025
This acid is created by gut bacteria as a protective mechanism and previous research from the team has shown it to extend the life of roundworms and fruit flies.
—New Atlas, 14 Nov. 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 23 Nov. 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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