The Collaborative International Dictionary of English v.0.48:

Formless \Form"less\, a.
   Shapeless; without a determinate form; wanting regularity of
   shape. -- Form"less*ly, adv. -- Form"less*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

formlessly
    adv 1: in a formless manner; "the dress hung formlessly on her
           body"