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
Self-cleaning mechanisms that employ steam work at lower temperatures than pyrolytic cleaning and don’t produce a burning smell.
—Jolie Kerr, Better Homes & Gardens, 7 Dec. 2025
Its design was inspired by the closing mechanism of the waterwheel plant (Aldrovanda vesiculosa).
—Georgina Jedikovska, Interesting Engineering, 6 Dec. 2025
Both governments highlighted progress made through mechanisms within the Shanghai Cooperation Organization (SCO) and BRICS, noting positive momentum in strengthening collective efforts.
—Hannah Parry, MSNBC Newsweek, 5 Dec. 2025
The editors of the journal said the authors misrepresented and selectively cited, or cherrypicked, data and that there were no valid justifications for the mechanisms the authors proposed for prevention.
—Jamie Gumbrecht, CNN Money, 5 Dec. 2025
See All Example Sentences for mechanism
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Jolie Kerr, Better Homes & Gardens, 7 Dec. 2025
Its design was inspired by the closing mechanism of the waterwheel plant (Aldrovanda vesiculosa).
—Georgina Jedikovska, Interesting Engineering, 6 Dec. 2025
Both governments highlighted progress made through mechanisms within the Shanghai Cooperation Organization (SCO) and BRICS, noting positive momentum in strengthening collective efforts.
—Hannah Parry, MSNBC Newsweek, 5 Dec. 2025
The editors of the journal said the authors misrepresented and selectively cited, or cherrypicked, data and that there were no valid justifications for the mechanisms the authors proposed for prevention.
—Jamie Gumbrecht, CNN Money, 5 Dec. 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 9 Dec. 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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