Source : Webster's Revised Unabridged Dictionary (1913)

Assertive \As*sert"ive\, a.
   Positive; affirming confidently; affirmative; peremptory.

         In a confident and assertive form.       --Glanvill.
   {As*sert"ive*ly}, adv. -- {As*sert"ive*ness}, n.

Source : WordNet®

assertive
     adj 1: inclined to bold and confident assertion; aggressively
            self-assured; "an energetic assertive boy who was
            always ready to argue"; "pointing directly at a
            listener is an assertive act" [ant: {unassertive}]
     2: confidently aggressive; "too assertive as a salesman"; "his
        self-assertive and unflagging energy" [syn: {self-asserting},
         {self-assertive}]