The Collaborative International Dictionary of English v.0.48:

Extraordinary \Ex*traor"di*na*ry\, n.; pl. Extraordinaries.
   That which is extraordinary; -- used especially in the
   plural; as, extraordinaries excepted, there is nothing to
   prevent success.
   [1913 Webster]

         Their extraordinary did consist especially in the
         matter of prayers and devotions.         --Jer. Taylor.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Extraordinary \Ex*traor"di*na*ry\, a. [L. extraordinarius; extra
   on the outside + ordinarius: cf. F. extraordinaire. See
   Ordinary.]
   1. Beyond or out of the common order or method; not usual,
      customary, regular, or ordinary; as, extraordinary evils;
      extraordinary remedies.
      [1913 Webster]

            Which dispose
            To something extraordinary my thoughts. --Milton.
      [1913 Webster]

   2. Exceeding the common degree, measure. or condition; hence,
      remarkable; uncommon; rare; wonderful; as, extraordinary
      talents or grandeur.
      [1913 Webster]

   3. Employed or sent upon an unusual or special service; as,
      an ambassador extraordinary.
      [1913 Webster]

WordNet (r) 3.0 (2006):

extraordinary
    adj 1: beyond what is ordinary or usual; highly unusual or
           exceptional or remarkable; "extraordinary authority"; "an
           extraordinary achievement"; "her extraordinary beauty";
           "enjoyed extraordinary popularity"; "an extraordinary
           capacity for work"; "an extraordinary session of the
           legislature" [ant: ordinary]
    2: far more than usual or expected; "an extraordinary desire for
       approval"; "it was an over-the-top experience" [syn:
       extraordinary, over-the-top, sinful]
    3: (of an official) serving an unusual or special function in
       addition to those of the regular officials; "an ambassador
       extraordinary"

Moby Thesaurus II by Grady Ward, 1.0:

132 Moby Thesaurus words for "extraordinary":
   abnormal, absolute, amazing, appalling, astonishing, astounding,
   beguiling, bewildering, bizarre, celebrated, certain, concrete,
   conspicuous, curious, defined, definite, detailed, determinate,
   different, distinct, distinguished, egregious, eminent, enigmatic,
   esoteric, especial, esteemed, estimable, exceptional, express,
   fabulous, fantastic, fascinating, fixed, formidable, gorgeous,
   impressive, improbable, incomprehensible, inconceivable,
   incredible, indescribable, individual, ineffable, inner, intimate,
   legendary, lovely, marked, marvelous, memorable, minute,
   miraculous, more than expected, mythical, noble, notable,
   noteworthy, noticeable, odd, of mark, out-of-the-way, outlandish,
   outstanding, particular, passing strange, past expectation,
   peculiar, personal, phenomenal, portentous, precise, prestigious,
   private, prodigious, prominent, puzzling, queer, rare, remarkable,
   rememberable, reputable, respective, salient, sensational, several,
   signal, singular, smashing, solipsistic, special, specific,
   strange, striking, stupefying, stupendous, sudden, super, superior,
   surprising, telling, terrific, unannounced, unanticipated,
   unbelievable, uncommon, undivined, unexampled, unexpected,
   unforeseeable, unforeseen, unforgettable, unguessed, unheard-of,
   unheralded, unhoped for, unimaginable, unique, unordinary,
   unparalleled, unprecedented, unpredictable, unpredicted,
   unprepared for, unreal, unspeakable, unthinkable, unusual,
   unwonted, without warning, wonderful, wondrous