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

El Niño is a naturally occurring weather cycle that occurs when trade winds over the Pacific weaken, causing warm water to pile up along the Pacific coast of equatorial South America. —Bill Kearney, Sun Sentinel, 16 May 2026

This year, the presence of an emerging El Niño and its associated warmer equatorial waters could mean a more active Eastern Pacific basin season. —Marshall Shepherd, Forbes.com, 15 May 2026

The boost in confidence is due to the vast pool of warm water that’s built up in the depths of the central and eastern equatorial Pacific in recent weeks. —Chris Dolce, CNN Money, 14 May 2026

El Niño refers to the warmer-than-average phase of the El Nino–Southern Oscillation (ENSO), a natural cycle where sea surface temperatures across the central and eastern equatorial Pacific Ocean rise and fall. —Dan Peck, ABC News, 14 May 2026

Word History

First Known Use

1664, in the meaning defined at sense 1a

Phrases Containing equatorial

• equatorial plane
• equatorial plate

Rhymes for equatorial

• arboreal
• armorial
• authorial
• factorial
• manorial
• memorial
• pictorial
• sartorial
• sectorial
• tutorial
• vectorial
• ambassadorial

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