Definition of "inseparable"

People of unalterable ideas still insisted upon calling him "Sergeant" when they met him, which was in some degree owing to his having still retained the well-shaped moustache of his military days, and the soldierly bearing inseparable from his form.

1874, Thomas Hardy, “Coming Home—A Cry”, in Far from the Madding Crowd. […], volume II, London: Smith, Elder & Co., […], pages 99–100

In the old days, to my commonplace and unobserving mind, he gave no evidences of genius whatsoever. He never read me any of his manuscripts, […] and therefore my lack of detection of his promise may in some degree be pardoned. But he had then none of the oddities and mannerisms which I hold to be inseparable from genius, and which struck my attention in after days when I came in contact with the Celebrity.

1897 December (indicated as 1898), Winston Churchill, chapter I, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd., page 1

=This detail is one of the reasons which made a single, modern signalbox and the marshalling yard inseparable features in the modernisation of the Perth facilities. A central control point rather than 13 individual boxes, was essential to integrate with other movements the greatly increased flow of freight traffic through the station area.

1962 October, G. Freeman Allen, “The New Look in Scotland's Northern Division—II”, in Modern Railways, page 271

Jayanta does so in answering an opponent who declares that the very idea of a relation between two inseparables is self-contradictory. How can inseparability and relation be reconciled?

2002, Brian Carr, Indira Mahalingam, Companion Encyclopedia of Asian Philosophy, page 129