- a fully mature female horse or other equine animal.
- 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.
- Marine Engineer.
- the adult female of a horse or zebra
- 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)
- a similar area on the surface of Mars, such as Mare Sirenum
