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
Then there's the homeostatic sleep drive, which is the other major biological mechanism that regulates sleep.
—NPR, 2 Nov. 2025
The mechanism that agricultural commissioners for Yuba and Sutter counties have at their disposal to curb theft is the annual walnut-buying period that establishes time frames and documentation requirements for buying and selling unprocessed walnuts.
—Jake Goodrick, Sacbee.com, 31 Oct. 2025
The team proposes a few different mechanisms that could account for the unexpectedly rapid brightening of this comet from beyond the solar system.
—Robert Lea, Space.com, 31 Oct. 2025
Richard Mille dropped a world timer with an ingenious time-zone setting mechanism.
—Rachel Cormack, Robb Report, 31 Oct. 2025
See All Example Sentences for mechanism
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NPR, 2 Nov. 2025
The mechanism that agricultural commissioners for Yuba and Sutter counties have at their disposal to curb theft is the annual walnut-buying period that establishes time frames and documentation requirements for buying and selling unprocessed walnuts.
—Jake Goodrick, Sacbee.com, 31 Oct. 2025
The team proposes a few different mechanisms that could account for the unexpectedly rapid brightening of this comet from beyond the solar system.
—Robert Lea, Space.com, 31 Oct. 2025
Richard Mille dropped a world timer with an ingenious time-zone setting mechanism.
—Rachel Cormack, Robb Report, 31 Oct. 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 8 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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