The Collaborative International Dictionary of English v.0.48:

Frump \Frump\, v. t. [Cf. Prov. E. frumple to wrinkle, ruffle,
   D. frommelen.]
   To insult; to flout; to mock; to snub. [Obs.] --Beau. & Fl.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Frump \Frump\, n.
   1. A contemptuous speech or piece of conduct; a gibe or
      flout. [Obs.] --Beau. & Fl.
      [1913 Webster]

   2. A cross, old-fashioned person; esp., an old woman; a
      gossip. [Colloq.] --Halliwell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

frump
    n 1: a dull unattractive unpleasant girl or woman; "she got a
         reputation as a frump"; "she's a real dog" [syn: frump,
         dog]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "frump":
   beldam, crone, dame, dowager, drab, grandam, grandmother, granny,
   hag, litterbug, old battle-ax, old dame, old girl, old granny,
   old lady, old trot, old wife, old woman, pig, schlep, schlump,
   slattern, slob, sloppy Joe, sloven, slut, swine, trollop, trot,
   war-horse, witch