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

That requires visibility below the operating system, control that persists through disruption, and recovery mechanisms that do not depend on fragile software layers. —CBS News, 22 Jan. 2026

The mechanism is controlled by a central pulley system as opposed to complex hardware to help keep weight down. —Bryan Hood, Robb Report, 22 Jan. 2026

The law also features enforcement mechanisms, which include FTC cease-and-desist orders, findings of unfair and deceptive trade practices and the capacity of states’ attorneys general to bring SPARTA cases. —Michael McCann, Sportico.com, 22 Jan. 2026

For developing countries, reforming the dispute settlement mechanism and restoring a functioning appellate body, the highest court for trade disputes, will be a priority to protect market access and effectively uphold their rights. —Jasmin Malik Chua, Sourcing Journal, 22 Jan. 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
• 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