A frumpy girl means that the girl is someone who dresses in old fashioned and unattractive, drab or shapeless clothing.
A frumpy girl or frump girl also known as frump is an informal and disapproving term that is used for describing a girl or woman that dresses in old fashioned, unattractive, shapeless or drab clothing.
The key characteristics of a frumpy girl are that she wears loose, outdated, modest or even poorly fitted clothing like bulky sweaters, long rigid skirts or unstylish flat shoes, instead of modern or flattering fashions.
Being frumpy is often perceived as dull, traditional, boring or lacking attention to personal style and calling someone a frump or describing the person as frumpy is generally not a compliment.
Common synonyms of frumpy are "Dowdy" which means dressed in a dull or old fashioned way, drab or unfashionable or staid or stick in the mud which is used for personality traits that is often paired with the look.
Frumpy is not a slur.
While "Frumpy" is not a slur it still is a derogatory or even insulting adjective.
The word "Frumpy" is a word that is used to describe someone, and almost always a woman or their clothing as being old fashioned, drab, unfashionable or even messy.
Although the word frumpy is an unkind and critical and often sexist judgement about a persons appearance, the word frumpy does not fit the definition of a slur.
The reason why the word frumpy does not fit the definition of a slur is because a slur is a deeply offensive and harmful term that is directed at a group of people that is based on their protected characteristics like race, religion, ethnicity, sexual orientation, or disability.
"Frumpy" is what simply describes a perceived lack of style or neatness.