A mare can refer to different things depending on the context. Here are the different meanings of the word:

• Horse: A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. Mares carry their young (called foals) for approximately 11 months from conception to birth. Usually, just one young is born; twins are rare. When a domesticated mare foals, she nurses the foal for at least four to six months before it is weaned, though mares in the wild may allow a foal to nurse for up to a year. Some mares, usually of draft horse breeding, are kept in North America for the production of their urine. Pregnant mares urine is the source of the active ingredient in the hormonal drug Premarin.

• Moon: Mare is also a term used to describe any flat, dark plain of lower elevation on the Moon. The term, which in Latin means “sea,” was erroneously applied to such features by telescopic observers of the 17th century. In actuality, maria are huge basins containing lava flows marked by craters, ridges, faults, and straight and meandering valleys called rilles and are devoid of water. There are about 20 major areas of this type, most of them—including the largest ones—located on the side of the Moon that always faces Earth. Maria are the largest topographic features on the Moon and can be seen from Earth with the unaided eye.

• Derogatory term: In some contexts, mare can be used as a derogatory term to refer to a woman, showing a lack of respect.

• Difficult situation: In the UK, mare can also be used informally to describe a difficult or unpleasant situation or experience.

In summary, a mare can refer to an adult female horse or other equine, a flat, dark plain of lower elevation on the Moon, a derogatory term for a woman, or a difficult situation.