limbo (n.1)

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 singular of limbus "edge, border" (see limb (n.2)). In frequent use in Latin phrases such as in limbo (patrum), which is entirely Latin, but the in was taken as English and hence the Latin ablative became the English noun. Figurative sense of "condition of neglect or oblivion, place of confinement" is from 1640s.

limbo (n.2)

dance in which the dancer bends backward and passes under a bar, 1956, of West Indian origin, probably an alteration of limber (adj.).