The Collaborative International Dictionary of English v.0.48:

Imputation \Im`pu*ta"tion\, [L. imputatio an account, a charge:
   cf. F. imputation.]
   [1913 Webster]
   1. The act of imputing or charging; attribution; ascription;
      also, anything imputed or charged.
      [1913 Webster]

            Shylock. Antonio is a good man.
            Bassanio. Have you heard any imputation to the
            contrary?                             --Shak.
      [1913 Webster]

            If I had a suit to Master Shallow, I would humor his
            men with the imputation of being near their master.
                                                  --Shak.
      [1913 Webster]

   2. Charge or attribution of evil; censure; reproach;
      insinuation.
      [1913 Webster]

            Let us be careful to guard ourselves against these
            groundless imputation of our enemies. --Addison.
      [1913 Webster]

   3. (Theol.) A setting of something to the account of; the
      attribution of personal guilt or personal righteousness of
      another; as, the imputation of the sin of Adam, or the
      righteousness of Christ.
      [1913 Webster]

   4. Opinion; intimation; hint.
      [1913 Webster]

WordNet (r) 3.0 (2006):

imputation
    n 1: a statement attributing something dishonest (especially a
         criminal offense); "he denied the imputation"
    2: the attribution to a source or cause; "the imputation that my
       success was due to nepotism meant that I was not taken
       seriously"

Moby Thesaurus II by Grady Ward, 1.0:

130 Moby Thesaurus words for "imputation":
   accounting for, accusal, accusation, accusing, adverse criticism,
   allegation, allegement, animadversion, answerability, application,
   arraignment, arrogation, ascription, aspersion, assignation,
   assignment, attachment, attaint, attribution, bad notices,
   bad press, badge of infamy, bar sinister, baton, bend sinister,
   bill of particulars, black eye, black mark, blame, blot, blur,
   brand, bringing of charges, bringing to book, broad arrow,
   captiousness, carping, cavil, caviling, censoriousness, censure,
   challenge, champain, charge, complaint, connection with, count,
   credit, criticism, delation, denouncement, denunciation,
   derivation from, disparagement, etiology, exception, faultfinding,
   flak, hairsplitting, hit, home thrust, honor, hostile criticism,
   hypercriticalness, hypercriticism, impeachment, implication,
   indictment, information, innuendo, insinuation, knock, lawsuit,
   laying of charges, mark of Cain, nagging, niggle, niggling, nit,
   nit-picking, obloquy, onus, overcriticalness, palaetiology,
   personal remark, personality, pestering, pettifogging, pillorying,
   placement, plaint, point champain, priggishness, prosecution,
   quibble, quibbling, rap, reference to, reflection, reprimand,
   reproach, reproachfulness, responsibility, saddling, slam, slur,
   sly suggestion, smear, smirch, smudge, smutch, spot, stain, stigma,
   stigmatism, stigmatization, stricture, suggestion, suit, swipe,
   taint, taking exception, tarnish, taxing, trichoschistism,
   true bill, uncomplimentary remark, unspoken accusation,
   veiled accusation, whispering campaign



Easton's 1897 Bible Dictionary:

Imputation
   is used to designate any action or word or thing as reckoned to
   a person. Thus in doctrinal language (1) the sin of Adam is
   imputed to all his descendants, i.e., it is reckoned as theirs,
   and they are dealt with therefore as guilty; (2) the
   righteousness of Christ is imputed to them that believe in him,
   or so attributed to them as to be considered their own; and (3)
   our sins are imputed to Christ, i.e., he assumed our
   "law-place," undertook to answer the demands of justice for our
   sins. In all these cases the nature of imputation is the same
   (Rom. 5:12-19; comp. Philemon 1:18, 19).