Other forms: bare bones
Something that is bare bone has nothing but the essential, basic elements. A bare bone speech is short, simple, and direct.
When something is bare bone — or bare bones — it doesn't have a lot of frills or bells and whistles. Like a skeleton, which is literally a bunch of bare bones, anything described as bare bone has been stripped down to the basics. A bare bone staff at a hospital will have just enough people to keep the hospital running. A bare bone bus schedule will have very few stops. Bare bone things have been whittled down to the essentials.