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

One is in the Northwestern Pacific, east of the Philippines and south of Japan; the second is in the Central Pacific, between Hawaii and the equatorial Western Pacific, and the third is in the South Pacific, east of Australia and north of New Zealand. —Anna Skinner, MSNBC Newsweek, 31 Mar. 2026

However, in 2021 and 2022, there was a lull in storms in Jupiter's north equatorial belt. —Charles Q. Choi, Space.com, 26 Mar. 2026

In many past El Niño events, that subsurface warmth gradually rises and spreads eastward across the equatorial Pacific, helping establish the warmer ocean temperatures that define El Niño. —Newsroom Meteorologist, Houston Chronicle, 17 Mar. 2026

During El Niño phases, east-to-west trade winds over the equatorial Pacific relax, causing warm surface water to accumulate off the Pacific coast of Central and South American. —Bill Kearney, Sun Sentinel, 17 Mar. 2026

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