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mare

1 American  
[mair] / mɛər /

noun

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


mare 2 American  
[mair] / mɛər /

noun

Obsolete.
  1. nightmare.


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.


mare 1 British  
/ mɛə /

noun

  1. the adult female of a horse or zebra

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

mare 2 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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

mare Scientific  
/ märā /
  • 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


Other Word Forms

Noun Inflected Forms

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.

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Vocabulary lists containing mare

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

Those horses, clones of the Polo Hall of Fame mare Polo Pureza, have an edit in a gene that regulates muscle development.

From The Wall Street Journal Jun. 6, 2026

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

O’Neill counters in those races with Civil Liberty and Listenupshance, while Richard Baltas will seek a second straight win with the mare Ag Bullet against males in the Grade 1 Jaipur.

From Los Angeles Times Jun. 2, 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

And every evening, the night mare took him to Petey’s house.

From "Bone Gap" by Laura Ruby

The research team set out to systematically map these ridges across the lunar maria and investigate their role in recent tectonic activity.

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

This result is similar to the age determined for the maria from radioactive dating of returned samples—3.3 to 3.8 billion years old.

From Textbooks Oct. 13, 2016

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

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