The Collaborative International Dictionary of English v.0.48:

Unexceptionable \Un`ex*cep"tion*a*ble\, a.
   Not liable to any exception or objection; unobjectionable;
   faultless; good; excellent; as, a man of most unexceptionable
   character. -- Un`ex*cep"tion*a*ble*ness, n. --
   Un`ex*cep"tion*a*bly, adv.
   [1913 Webster]
   [1913 Webster]

         Chesterfield is an unexceptionable witness. --Macaulay.
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