The Collaborative International Dictionary of English v.0.48:
Slimly \Slim"ly\, adv. In a state of slimness; in a slim manner; slenderly. [1913 Webster]WordNet (r) 3.0 (2006):
slimly adv 1: in a slim or slender manner; "a slenderly built woman"; "slightly built" [syn: slenderly, slimly, slightly]