mare

¹ American  

[mair] / mɛər /

noun

1. a fully mature female horse or other equine animal.

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mare ² American  

[mair] / mɛər /

noun

Obsolete.

1. nightmare.

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mare ³ American  

[mahr-ey, mair-ee] / ˈmɑr eɪ, ˈmɛər i /

noun

Astronomy.

• maria
  plural

1. any of the several large, dark plains on the moon and Mars: Galileo believed that the lunar features were seas when he first saw them through a telescope.

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mare ¹ British  

/ mɛə /

noun

1. the adult female of a horse or zebra

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mare ² British  

/ ˈmɑːreɪ /

noun

1. (capital when part of a name) any of a large number of huge dry plains on the surface of the moon, visible as dark markings and once thought to be seas: Mare Imbrium ( Sea of Showers )

2. a similar area on the surface of Mars, such as Mare Sirenum

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mare Scientific  

/ mä′rā /

• maria
  plural

1. Any of the large, low-lying dark areas on the Moon or on Mars or other inner planets. The lunar maria are believed to consist of volcanic basalts, and many are believed to be basins formed initially by large impacts with meteoroids and later filled with lava flows.

2. Compare terra

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Other Word Forms

Noun Inflected Forms

• maria
  plural

Etymology

Origin of mare¹

First recorded before 900; Middle English, mere, mare, maire “horse for riding; beast of burden,” Old English mere, myre “mare”; cognate with Old Frisian merie, Dutch merrie, German Mähre, Old Norse merr; the feminine equivalents to Old English mearh, Old High German marah, march, Old Norse marr, Irish marc, “horse, steed”; see also marshal

Origin of mare²

First recorded before 900; Middle English mare “night goblin; incubus,” Old English mære, mare, mere “nightmare; monster that oppresses people in their sleep”; cognate with German Mahre, Old Norse mara; see nightmare

Origin of mare³

First recorded in 1760–70; from Latin: literally, “sea”

Explanation

A mare is an adult female horse. If your new horse is a filly, a female baby horse, she'll grow up to be a mare. Horse experts have many words to distinguish the age and sex of their animals, from foal, for any newborn horse, to stallion, a full grown male, to colt, a young male horse. Mares are known for being more easy-going than stallions, and because they're equally fast and powerful, they're as likely as males to be used for racing. Another meaning of mare ("sea" in Latin) is "dark areas of the moon," once believed to be actual oceans.

Example Sentences

See Examples For:

mare maria

Despite riding and competing on a clone, Krajewski said she wouldn’t consider cloning her Olympic gold-medal-winning mare, Amande de B’Neville.

From The Wall Street Journal ● Jun. 6, 2026

“The expectation is that…the mare will acquire sprinter-like characteristics that she did not previously have, while maintaining her other exceptional traits,” said Gabriel Vichera, co-founder and chief scientific officer of Kheiron.

From The Wall Street Journal ● Jun. 6, 2026

The Puma, who is 10-1 on the morning line, is a son of Eve of War, a mare Kahn owns with Hidden Brook Farm in Paris, Ky.

From Los Angeles Times ● Apr. 30, 2026

Dan Skelton will be represented by mare Panic Attack as he closes in on the UK trainers' championship for the first time.

From BBC ● Apr. 6, 2026

To hear Mother tell it that mare was steady as a rock, and Grandpa didn’t pay much attention when he rode her.

From "Educated" by Tara Westover

The close-up image of the Moon's surface includes dark areas known as maria and bright areas known as the highlands.

From BBC ● Sep. 18, 2026

Because SMRs form through the same type of faulting, moonquakes may also occur across the lunar maria wherever these ridges exist.

From Science Daily ● Feb. 18, 2026

In the process, they identified 1,114 previously unrecognized SMR segments across the near side lunar maria.

From Science Daily ● Feb. 18, 2026

It has a thicker crust, more craters and fewer maria, or plains where lava once flowed.

From New York Times ● Jun. 2, 2024

In between spring storms, Jake’s telescope allowed me to walk down the rills and climb the mountains and stroll the maria of the moon in my mind.

From "October Sky" by Homer Hickam

Related Words

• colt
• filly
• stallion