The Collaborative International Dictionary of English v.0.48:

Archetypical \Ar`che*typ"ic*al\, a.
   Relating to an archetype; archetypal.
   [1913 Webster]

WordNet (r) 3.0 (2006):

archetypical
    adj 1: representing or constituting an original type after which
           other similar things are patterned; "archetypal
           patterns"; "she was the prototypal student activist"
           [syn: archetypal, archetypical, prototypal,
           prototypic, prototypical]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "archetypical":
   antitypic, archetypal, archetypic, classic, consummate, developed,
   exemplary, expert, finished, fully developed, masterful, masterly,
   mature, matured, model, perfected, polished, proficient,
   prototypal, prototypic, quintessential, refined, ripe, ripened