The Collaborative International Dictionary of English v.0.48:

Connive \Con*nive"\ (k[o^]n*n[imac]v"), v. i. [imp. & p. p.
   Connived (-n[imac]vd"); p. pr. & vb. n. Conniving.] [L.
   connivere to shut the eyes, connive, fr. con- + (perh.) a
   word akin to nicere to beckon, nictare to wink.]
   1. To open and close the eyes rapidly; to wink. [Obs.]
      [1913 Webster]

            The artist is to teach them how to nod judiciously,
            and to connive with either eye.       --Spectator.
      [1913 Webster]

   2. To close the eyes upon a fault; to wink (at); to fail or
      forbear by intention to discover an act; to permit a
      proceeding, as if not aware of it; -- usually followed by
      at.
      [1913 Webster]

            To connive at what it does not approve. --Jer.
                                                  Taylor.
      [1913 Webster]

            In many of these, the directors were heartily
            concurring; in most of them, they were encouraging,
            and sometimes commanding; in all they were
            conniving.                            --Burke.
      [1913 Webster]

            The government thought it expedient, occasionally,
            to connive at the violation of this rule.
                                                  --Macaulay.
      [1913 Webster]

WordNet (r) 3.0 (2006):

conniving
    adj 1: acting together in secret toward a fraudulent or illegal
           end [syn: collusive, conniving]
    2: used of persons; "the most calculating and selfish men in the
       community" [syn: calculating, calculative, conniving,
       scheming, shrewd]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "conniving":
   Byzantine, Machiavellian, calculating, coacting, coactive,
   coadjutant, coadjuvant, coefficient, collaborative, collective,
   collectivist, collectivistic, collusive, combined, commensal,
   common, communal, communalist, communalistic, communist,
   communistic, communitarian, concerted, concordant, concurrent,
   concurring, connivent, conspiring, contriving, cooperant,
   cooperating, cooperative, designing, ecumenic, fellow, harmonious,
   harmonized, intriguing, joint, mutual, noncompetitive, plotting,
   reciprocal, scheming, stratagemical, symbiotic, synergetic,
   synergic, synergistic, uncompetitive, up to