influential

from WordNet (r) 3.0 (2006)

influential
    adj 1: having or exercising influence or power; "an influential
           newspaper"; "influential leadership for peace" [ant:
           {uninfluential}]

from The Collaborative International Dictionary of English v.0.48

Influential \In`flu*en"tial\ ([i^]n`fl[-u]*[e^]n"shal), a. [See
   {Influence}.]
   Exerting or possessing influence or power; potent;
   efficacious; effective; strong; having authority or
   ascendency; as, an influential man, station, argument, etc.
   [1913 Webster]

         A very influential Gascon prefix.        --Earle.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

62 Moby Thesaurus words for "influential":
      absolute, ascendant, authoritarian, authoritative, authorized,
      autocratic, charismatic, charming, clothed with authority,
      commanding, competent, consequential, considerable, controlling,
      dominant, duly constituted, effective, effectual, efficacious,
      eminent, empowered, enchanting, estimable, ex officio, forceful,
      governing, great, guiding, hegemonic, hegemonistic, imperative,
      important, instrumental, leading, magnetic, mighty, momentous,
      monocratic, official, personable, persuasive, potent, powerful,
      predominant, preeminent, prestigious, prominent, puissant, ranking,
      reputable, ruling, senior, significant, strong, suasive,
      substantial, superior, supreme, telling, totalitarian, weighty,
      winning