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.

plural

maria

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  

/ ˈmɑːreɪ, -rɪ /

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 ² British  

/ mɛə /

noun

1. the adult female of a horse or zebra

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mare Scientific  

/ mä′rā /

plural

maria

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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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

It was the third win in five career starts for Golden Tempo, a son of Curlin and the Bernardini mare Carrumba.

From Los Angeles Times • May 2, 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

Another class of landforms, small mare ridges, has also been identified.

From Science Daily • Feb. 18, 2026

I looked up and saw the little mare come limping across the barn lot.

From "Summer of the Monkeys" by Wilson Rawls

Related Words

• colt
• filly
• stallion