Is it ensure, insure, or assure?
"region supposed to exist on the border of Hell" reserved for pre-Christian saints (Limbus patrum) and unbaptized infants (Limbus infantum);" c.1300, from Latin limbo, ablative of limbus "edge, border" (see limb (2)). It emerged from Latin in the ablative form from frequent use in phrases such as in limbo (patrum), etc. Figurative sense of "condition of neglect or oblivion" is from 1640s.
dance in which the dancer bends backward and passes under a bar, 1956, of W.Indian origin, probably an alteration of limber.
In the teaching of the Roman Catholic Church regarding the afterlife, the condition of innocent persons who die without benefit of baptism; those in limbo do not suffer damnation, but they do not enjoy the presence of God. Limbo means “a bordering place.”
Note: Figuratively, “limbo” is a state of nonresolution or uncertainty: “Until he receives notice of his new posting, he'll be in limbo.”