frump 
(frŭmp)
(frŭmp)n.
1. A girl or woman regarded as dull, plain, or unfashionable.
2. A person regarded as colorless and primly sedate.
[Possibly short for Middle English frumple, wrinkle, from Middle Dutch verrompelen, to wrinkle : ver-, completely; see per1 in the Appendix of Indo-European roots + rompelen, to wrinkle.]
frumpi·ly adv.
frumpi·ness n.
frumpy adj.