The Collaborative International Dictionary of English v.0.48:

Unalienable \Un*al"ien*a*ble\, a.
   Inalienable; as, unalienable rights. --Swift. --
   Un*al"ien*a*bly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unalienable
    adj 1: incapable of being repudiated or transferred to another;
           "endowed by their Creator with certain unalienable
           rights" [syn: inalienable, unalienable] [ant:
           alienable]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "unalienable":
   deep-seated, esoteric, immanent, implanted, implicit, inalienable,
   indwelling, infixed, ingrained, inherent, inner, internal,
   intrinsic, inward, inwrought, irreducible, private, resident,
   secret, subjective, unchallengeable, unquestionable



Bouvier's Law Dictionary, Revised 6th Ed (1856):

UNALIENABLE. The state of a thing or right which cannot be sold.
     2. Things which are not in commerce, as public roads, are in their
nature unalienable. Some things are unalienable, in consequence of
particular provisions in the law forbidding their sale or transfer, as
pensions granted by the government. The natural rights of life and liberty
are unalienable.