The Collaborative International Dictionary of English v.0.48:
Filthily \Filth"i*ly\, adv. In a filthy manner; foully. [1913 Webster]WordNet (r) 3.0 (2006):
filthily adv 1: in a filthy unclean manner; "a dirtily dressed camel driver" [syn: dirtily, filthily]