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

• tropical
• subtropical

Examples of equatorial in a Sentence

a lush equatorial rain forest that is threatened by rampant development

Recent Examples on the Web

Far from the equatorial lowlands where these swamps formed, polar glaciers steadily marched on the midlatitudes and threatened to take over the entire planet. —Peter Brannen, Quanta Magazine, 15 Sep. 2025

Another factor is the Quasi-Biennial Oscillation (QBO), a 24–28-month cycle in which equatorial winds shift east to west. —Joe Edwards, MSNBC Newsweek, 29 Aug. 2025

From the rainforests of Central and South America to the savannas of northern Australia, the world’s equatorial regions are home to thousands of unique bird species, from macaws to toucans to hummingbirds, who thrive in hot and humid environments. —Lex Harvey, CNN Money, 13 Aug. 2025

Other red supergiants in binary or multiple star systems display equatorial rings in their circumstellar material driven by the orbital interactions of a companion star. —Keith Cooper, Space.com, 13 Aug. 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