As a Verb or Adjective:
1. Of a person or an animal, to have very little fat on its body. English = (be) thin, (be) skinny, (be) lean.
2. [With cheeks sucked in], to be very thin. English = (be) gaunt.
3. Of anything, to have a small distance between its two opposite surfaces. English = (be) thin, (be) narrow.