apparatus

noun

ap·​pa·​ra·​tus ˌa-pə-ˈra-təs  -ˈrā- 

plural apparatuses or apparatus

1

a

: a set of materials or equipment designed for a particular use

b

: a group of anatomical or cytological parts functioning together

mitotic apparatus

c

: an instrument or appliance designed for a specific operation

an apparatus for measuring vision

2

: the functional processes by means of which a systematized activity is carried out

the apparatus of society

: such as

a

: the machinery of government

b

: the organization of a political party or an underground movement

Synonyms of apparatus

• equipment
• gear

Examples of apparatus in a Sentence

Recent Examples on the Web

Over the course of several years, the company tested the apparatus about 200,000 times to achieve the right effect, culminating in a patented design. —Justin Fenner, Robb Report, 31 Jan. 2026

The fall of the ayatollah could empower the Islamic Revolutionary Guard Corps, or IRGC, a powerful branch of Iran’s security apparatus that operates independently of the nation’s armed forces. —Vivian Salama, The Atlantic, 30 Jan. 2026

The detector itself is a 26-meter-long, 16-meter-tall cylindrical apparatus weighing 10,000 tonnes. —Tejasri Gururaj, Interesting Engineering, 29 Jan. 2026

Two dozen fire personnel and 10 pieces of fire apparatus were dispatched to the scene and extinguished the blaze in less than 10 minutes. —Naperville Sun, Chicago Tribune, 29 Jan. 2026

Word History

Etymology

borrowed from Latin apparātus "act of preparing, display, trappings, equipment," from apparāre "to make ready, make preparations for" (from ad- ad- + parāre "to supply, provide, make ready") + -tus, suffix of verbal nouns — more at pare

First Known Use

circa 1628, in the meaning defined at sense 1a

Phrases Containing apparatus

• Golgi apparatus

Rhymes for apparatus

• superlattice
• beatus
• flatus
• gratis
• lattice
• rattus
• satis
• status
• stratus

Kids Definition

apparatus

noun

ap·​pa·​ra·​tus ˌap-ə-ˈrat-əs  -ˈrāt- 

plural apparatuses or apparatus

1

: the equipment or material for a particular use or job

laboratory apparatus

2

: a complicated instrument or device

Medical Definition

apparatus

noun

ap·​pa·​ra·​tus ˌap-ə-ˈrat-əs  -ˈrāt- 

plural apparatuses or apparatus

: a group of anatomical and cytological parts having a common function

the respiratory apparatus

see golgi apparatus