The Collaborative International Dictionary of English v.0.48:

Inalienable \In*al"ien*a*ble\, a. [Pref. in- not + alienable:
   cf. F. inali['e]nable.]
   Incapable of being alienated, surrendered, or transferred to
   another; not alienable; as, in inalienable birthright.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inalienable
    adj 1: incapable of being repudiated or transferred to another;
           "endowed by their Creator with certain unalienable
           rights" [syn: inalienable, unalienable] [ant:
           alienable]
    2: not subject to forfeiture; "an unforfeitable right" [syn:
       unforfeitable, inalienable]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "inalienable":
   bound up in, bound up with, deep-seated, esoteric, immanent,
   impartible, implanted, implicit, incommunicable, indefeasible,
   indissoluble, indivisible, indwelling, infixed, ingrained,
   inherent, inner, inseparable, internal, intrinsic, inward,
   inwrought, irreducible, noncommunicable, noncontagious,
   noninfectious, private, resident, secret, subjective, unalienable,
   unchallengeable, undividable, unimpartable, unquestionable



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

INALIENABLE. This word is applied to those things, the property of which
cannot be lawfully transferred from one person to another. Public highways
and rivers are of this kind; there are also many rights which are
inalienable, as the rights of liberty, or of speech.