Emily Dickinson Lexicon

WELK, v.i. [G. and D. welken, to wither, to fade, to decay; primarily to shrink or contract, as things in drying, whence the Saxon weolc, a whilk or whelk, a shell; from its wrinkles.]

To decline; to fade; to decay; to fall. When ruddy Phœbus 'gins to welk in west. – Spenser. [Obs.]