WordNet (r) 3.0 (2006):

expertise
    n 1: skillfulness by virtue of possessing special knowledge
         [syn: expertness, expertise]

Moby Thesaurus II by Grady Ward, 1.0:

109 Moby Thesaurus words for "expertise":
   ability, acquaintance, address, adeptness, adroitness, aesthetics,
   airmanship, all-knowingness, art, artfulness, artisanship,
   artistic taste, artistry, bravura, brilliance, capability,
   capacity, cleverness, command, competence, connoisseurship,
   control, coordination, corpus, craft, craftsmanship,
   cross-disciplinary knowledge, cunning, data, datum, deep knowledge,
   deftness, dexterity, dexterousness, dextrousness, dilettantism,
   diplomacy, efficiency, encyclopedic knowledge, epicureanism,
   epicurism, experience, expertism, expertness, extensive knowledge,
   facility, facts, factual base, familiarity, finesse, friandise,
   gastronomy, general knowledge, grace, grip, handiness,
   horsemanship, information, ingeniousness, ingenuity, intelligence,
   intimacy, judgement, ken, knack, know-how, knowing, knowledge,
   marksmanship, mastership, mastery, omniscience, pansophy,
   polyhistory, polymathy, practical ability, practical knowledge,
   private knowledge, privity, proficiency, profound knowledge,
   prowess, quickness, ratio cognoscendi, readiness, resource,
   resourcefulness, savoir-faire, savvy, seamanship, self-knowledge,
   skill, skillfulness, special knowledge, style, tact, tactfulness,
   technic, technical brilliance, technical mastery, technical skill,
   technics, technique, timing, virtu, virtuosity, wit, wizardry,
   workmanship