Definition of "inalienably"

This was his intention to persuade their aged grandfather to transfer his own heirship to Arthur, which he considered it a fortunate circumstance was in his power, with the exception of a very small estate, tied inalienably to the heir of that ancient and distinguished family.

1838 (date written), L[etitia] E[lizabeth] L[andon], chapter XXI, in Lady Anne Granard; or, Keeping up Appearances. […], volume I, London: Henry Colburn, […], published 1842, page 263