TORONTO, Dec 4 (Reuters) - The Canadian dollar weakened to a fresh three-year low against the greenback on Wednesday after the Bank of Canada held its interest rate steady but sounded a touch more dovish in its outlook. The Canadian dollar was at C$1.0680 to the greenback, or 93.63 U.S. cents, weaker than Tuesday's close of C$1.0649 or 93.91 U.S. cents. The loonie hit a session low of C$1.0698 shortly after the decision was released.