unheard of

from The Collaborative International Dictionary of English v.0.48
Unheard \Un*heard"\, a.
   1. Not heard; not perceived by the ear; as, words unheard by
      those present.
      [1913 Webster]

   2. Not granted an audience or a hearing; not allowed to
      speak; not having made a defense, or stated one's side of
      a question; disregarded; unheeded; as, to condem? a man
      unheard.
      [1913 Webster]

            What pangs I feel, unpitied and unheard! --Dryden.
      [1913 Webster]

   3. Not known to fame; not illustrious or celebrated; obscure.
      [1913 Webster]

            Nor was his name unheard or unadored. --Milton.
      [1913 Webster]

   {Unheard of}.
      (a) Not heard of; of which there are no tidings.
      (b) Unknown to fame; obscure. --Glanvill.
          [1913 Webster]
    
from Moby Thesaurus II by Grady Ward, 1.0
94 Moby Thesaurus words for "unheard of":
      able, beguiling, bewildering, breakaway, different, enigmatic,
      exceptional, extraordinary, fabulous, fantastic, fascinating,
      ignotus, incalculable, incognizable, incomprehensible,
      inconceivable, incredible, inglorious, little known, marvelous,
      miraculous, mysterious, nameless, no credit to, novel, obscure,
      offbeat, original, outlandish, passing strange, phenomenal,
      prodigious, puzzling, rare, recherche, remarkable, renownless,
      sealed, sensational, strange, striking, stupendous, sui generis,
      unapparent, unapprehended, unascertained, unbeknown, uncelebrated,
      uncharted, unclassified, uncommon, uncustomary, undisclosed,
      undiscoverable, undiscovered, undistinguished, undivulged,
      undreamed-of, unexpected, unexplained, unexplored, unexposed,
      unfamed, unfamiliar, unfathomed, unglorified, unheard, unhonored,
      unidentified, unimaginable, uninvestigated, unique, unknowable,
      unknown, unnotable, unnoted, unnoticed, unordinary, unperceived,
      unplumbed, unpopular, unprecedented, unremarked, unrenowned,
      unrevealed, unsung, unsuspected, unthought-of, untouched, unusual,
      unwonted, virgin, wonderful, wondrous

    

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