The Collaborative International Dictionary of English v.0.48:

Unadorned \Unadorned\
   See adorned.

WordNet (r) 3.0 (2006):

unadorned
    adj 1: not decorated with something to increase its beauty or
           distinction [syn: unadorned, undecorated] [ant:
           adorned, decorated]

Moby Thesaurus II by Grady Ward, 1.0:

95 Moby Thesaurus words for "unadorned":
   Spartan, arcadian, ascetic, austere, bald, bare, basic, blank,
   bucolic, candid, chaste, common, commonplace, direct, dry, dull,
   elementary, essential, frank, fundamental, genuine, homely,
   homespun, homogeneous, inartificial, indivisible, irreducible,
   lean, matter-of-fact, mere, monolithic, naked, native, natural,
   naturelike, neat, nude, of a piece, open, pastoral, plain,
   plain-speaking, plain-spoken, primal, primary, prosaic, prosing,
   prosy, pure, pure and simple, rural, rustic, severe, sheer,
   simon-pure, simple, simple-speaking, single, sober, spare, stark,
   straightforward, unadulterated, unaffected, unarrayed,
   unartificial, unassuming, uncluttered, uncomplicated, undecked,
   undecorated, undesigning, undifferenced, undifferentiated,
   undisguising, undissembling, undissimulating, undressed,
   unelaborate, unembellished, unenhanced, unfeigning, unfurbished,
   ungarnished, uniform, unimaginative, unornamented, unostentatious,
   unpoetical, unpretending, unpretentious, unsophisticated,
   unspoiled, untrimmed, unvarnished