Definition of "shamefast"

With chaunge of cheare the seeming simple maid / Let fall her eyen, as shamefast to the earth [...].

1590, Edmund Spenser, “Book I, Canto II”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie

But the women are alwayes covered about their middles with a skin, and very shamefast to be seene bare.

1624, John Smith, Generall Historie, Kupperman, published 1988, page 141