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

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

At a minimum, effective infrastructure includes robust reporting mechanisms, swift response protocols, and consistent accountability measures - regardless of sector and size of organizations. —Aparna Rae, Forbes.com, 6 June 2025

Trump was under particular pressure from American auto suppliers, who wrote a letter decrying Chinese export controls, particularly the rare-earth magnets that are essential to key components including brakes and steering mechanisms — as well as semiconductors used in smartphones and laptops. —Michael Barclay, Quartz, 6 June 2025

Most of this carnivorous botany is small, but the diversity of different trapping mechanisms raises an evolutionary question. —Riley Black, Smithsonian Magazine, 6 June 2025

Without any clear enforcement mechanism, companies that use dyes in food could go through the motions with the administration while continuing to use dyes in perpetuity. —Andrea Ruth, The Washington Examiner, 6 June 2025

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
• statism
• sufism
• thomism
• tourism
• tropism
• abolitionism
• aldosteronism
• americanism

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