1911 Encyclopædia Britannica/Mare
MARE, the English term for the female of any animal of the family Equidae, of the ass, or zebra, but particularly of the horse. It is also used of the camel. To find a “mare’s nest” is an old proverbial saying for a purely imaginary discovery. In “night-mare,” an oppressive or terrifying dream, the termination is a word appearing as mar, maer and mara in various Teutonic languages for a goblin, supposed to sit on a sleeper’s chest and cause these dreams: cf. elf. This Teutonic word also appears in the French cauchemar, the first part being from caucher, to tread or trample upon, Lat. calcare.