Female horses, especially adult female horses.
From Old English 'mere' meaning female horse, possibly from a Proto-Germanic root. The term has been used for thousands of years to distinguish female horses from stallions (males) and geldings (castrated males).
Mares are surprisingly important in horse breeding—their behavior and genetics often determine the quality of the herd more than stallions! Interestingly, 'mare' may come from the same root as 'mother' in some Indo-European languages, though linguists debate this connection.
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