The Collaborative International Dictionary of English v.0.48:
Slatternly \Slat"tern*ly\, a. Resembling a slattern; sluttish; negligent; dirty. -- adv. In a slatternly manner. [1913 Webster]WordNet (r) 3.0 (2006):
slatternly adj 1: characteristic of or befitting a slut or slattern; used especially of women [syn: blowsy, blowzy, slatternly, sluttish]