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

2

: 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

3

: 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

Examples 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

Scientists had long understood the mechanism of climate change, but what was once an abstract concept on a graph is now a palpable experience. — Adam Frank, Forbes.com, 17 July 2026

Also, the folding mechanism keeps the panels entirely free of snow and reduces the steep winter efficiency losses that typically plague conventional solar systems. — Mrigakshi Dixit, Interesting Engineering, 17 July 2026

The hinge and swivel mechanisms provide 180 degrees of vertical and 360 degrees of horizontal movement. — Bestreviews, Mercury News, 17 July 2026

Brazil's President Luiz Inacio Lula da Silva in a statement posted on X rejected the tariff decision as groundless, and vowed to initiate countermeasures while raise the issue within the framework of the WTO dispute settlement mechanism. — Anniek Bao, CNBC, 16 July 2026

Word History

First Known Use

1662, in the meaning defined at sense 1a

Phrases Containing mechanism

• defense mechanism
• escape mechanism
• survival mechanism

Rhymes for mechanism

• autism
• fascism
• racism
• sikhism
• sophism
• statism
• sufism
• thomism
• tourism
• tropism
• abolitionism
• aldosteronism

Kids 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

mechanistic

ˌmek-ə-ˈnis-tik 

adjective