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

In the Chicago area, the mechanisms for alerting the public vary county by county, and, in some cases, city by city. —William Tong, Chicago Tribune, 14 July 2025

Designing solutions where payment lifecycles include strong alerting mechanisms is crucial. —Sunny Banerjee, Forbes.com, 14 July 2025

The July 1 reprogramming of USAID into the State Department cut two additional U.S. staffers dedicated to Sudan, leaving just nine remaining in the region, said Andrea Tracy, a former USAID Sudan official who now runs her own humanitarian funding mechanism for the country. —Chris Boccia, ABC News, 13 July 2025

Thanks to Trump, this enforcement mechanism no longer works. —Christiaan Hetzner, Fortune, 12 July 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