mousterious

Now, Marse George, you know dat dat's projickin 'wid de Lord's handy works, en sumpin mousterious en terrible is gwine ter happen ter dem niggers.

Documenting the American South: The Southern Experience in 19-th Century America 1913

He hath locktoes, this short-shins, and, Obeold that’s pectoral, his mammamuscles most mousterious.

Finnegans Wake 2006