"nightmare" and "bugbear"

[Max Dashu]

Joat Simeon writes,

>-- the Germanic "mare" is a derived feminine of PIE *markos ('horse',
>possibly 'wild horse'), with the feminine ending, -ih(a), thus *markiha

>>Old Norse merr, 'mare',  Old English miere, 'mare', Old High German meriha,
>'mare'.

>There's a Celtic cognate but only with the general meaning of "horse";
>Gaulish 'marco', Old Irish 'marc', Welsh 'march'.

There's another root, mahra, having to do with spirits and night hags. My
notes are all packed for moving, so I can't offer details, but variants of
this word are found across a wide range of IE languages.

Max Dashu