Source : Webster's Revised Unabridged Dictionary (1913)

Distrustful \Dis*trust"ful\, a.
   1. Not confident; diffident; wanting confidence or thrust;
      modest; as, distrustful of ourselves, of one's powers.

            Distrustful sense with modest caution speaks.
                                                  --Pope.

   2. Apt to distrust; suspicious; mistrustful. --Boyle. --
      {Dis*trust"ful*ly}, adv. -- {Dis*trust"ful*ness}, n.

Source : WordNet®

distrustful
     adj 1: having or showing distrust; "a man of distrustful nature";
            "my experience...in other fields of law has made me
            distrustful of rules of thumb generally"- B.N.Cardozo;
            "vigilant and distrustful superintendence"- Thomas
            Jefferson [ant: {trustful}]
     2: incredulous by virtue of distrust