limboyoudaoicibaDictYouDict[limbo 词源字典]
limbo: English has two distinct and probably unrelated words limbo. By far the older is the theological limbo [14], referring originally to that condition in which the souls of the dead exist that are neither in heaven nor in hell. It comes from Latin limbus ‘border, edge’, which in the Middle Ages was used to refer to a region on the borders of, but not actually inside, hell.

It very often turned up in the ablative case, in the phrase in limbo, which is how English adopted it. The other limbo [20], denoting a West Indian dance that involves passing underneath a progressively lowered bar, probably comes from limber ‘flexible, supple’ [16], which in turn might be from limb or possibly from limber ‘detachable forward part of a gun-carriage’ [15] (although spellings of that with a b do not occur before the 17th century).

No one knows where that limber came from, although it might ultimately be Celtic. Alternatively, if the bar is viewed as a sort of boundary that the dancer must cross, the terpsichorean limbo could be related to the theological limbo.
[limbo etymology, limbo origin, 英语词源]
limbo (n.1)youdaoicibaDictYouDict
"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.
limbo (n.2)youdaoicibaDictYouDict
dance in which the dancer bends backward and passes under a bar, 1956, of W.Indian origin, probably an alteration of limber.