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

• low
• tropical

Examples of equatorial in a Sentence

a lush equatorial rain forest that is threatened by rampant development

Recent Examples on the Web

While no definitive conclusions were reached, the team emphasizes that further research into shallow equatorial ice, lava erosion, and outflow channel processes is crucial for understanding Mars' history. —Victoria Corless, Space.com, 24 Jan. 2025

In this equatorial zone, what’s now Mallorca would have experienced very wet and very dry seasons. —Mindy Weisberger, CNN, 19 Dec. 2024

The northern equatorial upwelling front, which brings cold-nutrient rich waters to the surface, combined with the tropical sun is the perfect recipe for ocean productivity that sustains ocean pelagic food webs. —Melissa Cristina Marquez, Forbes, 22 Sep. 2024

In the photo, there's a line around the moon's equator that resembles the equatorial trench around the Death Star. —Ailsa Harvey, Space.com, 17 Jan. 2025

Word History

First Known Use

1664, in the meaning defined at sense 1a

Phrases Containing equatorial

• equatorial plane
• equatorial plate

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