unchallengeable

from WordNet (r) 3.0 (2006)

unchallengeable
    adj 1: not open to challenge; "unchallengeable facts"; "a
           position of unchallengeable supremacy"

from The Collaborative International Dictionary of English v.0.48

Unchallengeable \Unchallengeable\
   See {challengeable}.

from Moby Thesaurus II by Grady Ward, 1.0

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

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