equatorial

adjective

equa·​to·​ri·​al ˌē-kwə-ˈtȯr-ē-əl 

ˌe-kwə-

1

a

: of, relating to, or located at the equator or an equator

also : being in the plane of the equator

a satellite in equatorial orbit

b

: of, originating in, or suggesting the region around the geographic equator

2

a

: being or having a support that includes two axles at right angles to each other with one parallel to the earth's axis of rotation

an equatorial telescope mount

b

: extending in a direction essentially in the plane of a cyclic structure (as of cyclohexane)

equatorial hydrogens

compare axial

Synonyms of equatorial

• tropical
• subtropical

Examples of equatorial in a Sentence

a lush equatorial rain forest that is threatened by rampant development

Recent Examples on the Web

In an earlier era, the area around Goma, a region of vast lakes and forests, was the ivory belt of equatorial Africa, and the target of slaving expeditions from the Arab world. —Jon Lee Anderson, New Yorker, 24 Nov. 2025

La Niña is the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific Ocean, which occurs every three to five years. —Brayden Garcia, Fort Worth Star-Telegram, 20 Nov. 2025

This year, the El Niño-Southern Oscillation -- a natural variation of warmer, neutral and cooler waters along the equatorial waters of the eastern Pacific -- has been in the cooler pattern, or La Niña, since September and is expected to continue for much of winter. —Kenton Gewecke, ABC News, 19 Nov. 2025

Plus, England’s slightly more equatorial position ensured more consistent heat year-round. —Mrigakshi Dixit, Interesting Engineering, 12 Nov. 2025

Word History

First Known Use

1664, in the meaning defined at sense 1a

Phrases Containing equatorial

• equatorial plane
• equatorial plate

Rhymes for equatorial

• categorial
• curatorial
• dictatorial
• directorial
• editorial
• immemorial
• infusorial
• janitorial
• professorial
• reportorial
• senatorial
• territorial

Kids Definition

equatorial

adjective

equa·​to·​ri·​al ˌē-kwə-ˈtōr-ē-əl 

ˌek-wə-, 

-ˈtȯr-

1

: of, relating to, or located at the equator

2

: of, originating in, or suggesting the region around the equator

equatorial heat

Medical Definition

equatorial

adjective

equa·​to·​ri·​al ˌē-kwə-ˈtōr-ē-əl  ˌek-wə- 

-ˈtȯr-

1

: of, located at, or relating to an equator

equatorial diameter

2

: extending in a direction essentially in the plane of a cyclic structure (as of cyclohexane)

equatorial hydrogen atoms

compare axial sense 2b