The Collaborative International Dictionary of English v.0.48:

Dowdy \Dow"dy\, a. [Compar. Dowdier; superl. Dowdiest.]
   [Scot. dawdie slovenly, daw, da sluggard, drab, Prov. E. dowd
   flat, dead.]
   Showing a vulgar taste in dress; awkward and slovenly in
   dress; vulgar-looking. -- Dow"di*ly, adv. -- Dow"di*ness,
   n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dowdiness
    n 1: having a drab or dowdy quality; lacking stylishness or
         elegance [syn: dowdiness, drabness, homeliness]