Mare, n. [AS. mara incubus; akin to OHG. & Icel. mara; cf. Pol. mora, Bohem. můra.] (Med.) Sighing, suffocative panting, intercepted utterance, with a sense of pressure across the chest, occurring during sleep; the incubus; — obsolete, except in the compound nightmare.
I will ride thee o' nights like the mare. Shak.