'Limbus' definitions:

Definition of 'limbus'

noun

A border or edge of any of various body parts distinguished by color or structure

From: GCIDE

Limbo \Lim"bo\ (l[i^]m"b[-o]), Limbus \Lim"bus\ (l[i^]m"b[u^]s), n. [L. limbus border, edge in limbo on the border. Cf. Limb border.]
1. (Scholastic Theol.) An spiritual region where certain classes of souls were supposed to await the last judgment. [1913 Webster]
As far from help as Limbo is from bliss. --Shak. [1913 Webster]
A Limbo large and broad, since called The Paradise of fools. --Milton. [1913 Webster]
Note: The limbus patrum was considered as a place for the souls of good men who lived before the coming of our Savior. The limbus infantium was said to be a similar place for the souls of unbaptized infants. To these was added, in the popular belief, the limbus fatuorum, or fool's paradise, regarded as a receptacle of all vanity and nonsense. [1913 Webster]
2. Hence: Any real or imaginary place of restraint or confinement; a prison; as, to put a man in limbo. [1913 Webster]
3. Hence: A state of waiting, or uncertainty, in which final judgment concerning the outcome of a decision is postponed, perhaps indefinitely; neglect for an indefinite time; as, the proposal was left in limbo while opponents and proponents refused to compromise. [PJC]
4. (Anat.) A border or margin; as, the limbus of the cornea. [1913 Webster]