The Collaborative International Dictionary of English v.0.48:

Unexceptionable \Unexceptionable\
   See exceptionable.

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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unexceptionable
    adj 1: completely acceptable; not open to exception or reproach;
           "two unexceptionable witnesses"; "a judge's ethics should
           be unexceptionable" [syn: unexceptionable,
           unimpeachable]