IPA: /ˈslɪmli/
KK: /slɪmli/
In a way that is thin or slender.
She walked slimly through the crowd, trying not to bump into anyone.
Slimly → It is formed from "slim" (from Middle English *slim*, meaning slender or thin) and "-ly" (meaning in a manner of). The word "slimly" means in a slender or thin manner.
Think of someone moving in a 'slender' way — 'slim' describes that thinness, and '-ly' indicates the manner of doing it.