The Collaborative International Dictionary of English v.0.48:

Persuasive \Per*sua"sive\, a. [Cf. F. persuasif.]
   Tending to persuade; having the power of persuading; as,
   persuasive eloquence. "Persuasive words." --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Persuasive \Per*sua"sive\, n.
   That which persuades; an inducement; an incitement; an
   exhortation. -- Per*sua"sive*ly, adv. --
   Per*sua"sive*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

persuasive
    adj 1: intended or having the power to induce action or belief;
           "persuasive eloquence"; "a most persuasive speaker"; "a
           persuasive argument" [ant: dissuasive]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "persuasive":
   absolute, assuring, authoritative, bait, bribe, cajoling, carrot,
   charismatic, charming, cogent, compelling, conclusive,
   consequential, convictional, convincing, decisive, determinative,
   dynamic, effective, effectual, efficacious, enchanting,
   encouragement, estimable, exhortative, exhortatory, fillip,
   forceful, hortative, hortatory, important, impressive, incentive,
   incitement, inducement, influential, interest, invitation, lure,
   magnetic, momentous, payment, percentage, personable, persuading,
   potent, powerful, prestigious, productive, profit, provocation,
   reputable, reward, satisfactory, satisfying, stimulation,
   stimulative, stimulus, strong, suasive, substantial, sweetener,
   sweetening, telling, valid, weighty, wheedling, whet, winning