The Collaborative International Dictionary of English v.0.48:

M'etier \M['e]`tier"\, n. [F.]
   1. Calling; vocation; business; trade.

            Not only is it the business of no one to preach the
            truth but it is the m['e]tier of many to conceal it.
                                                  --A. R.
                                                  Colquhoun.
      [Webster 1913 Suppl.]

   2. the field or activity at which one excels; one's forte.
      [PJC] Metif

WordNet (r) 3.0 (2006):

metier
    n 1: an asset of special worth or utility; "cooking is his
         forte" [syn: forte, strong suit, long suit, metier,
         specialty, speciality, strong point, strength]
         [ant: weak point]
    2: an occupation for which you are especially well suited; "in
       law he found his true metier" [syn: metier, medium]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "metier":
   ability, area, art, bag, bump, business, caliber, calling,
   capability, capacity, career, career building, careerism, craft,
   cup of tea, dower, dowry, endowment, equipment, faculty, field,
   flair, forte, game, genius, gift, handicraft, instinct, lifework,
   line, line of business, line of work, long suit, main interest,
   makings, manner, medium, mission, mystery, natural endowment,
   natural gift, number, occupation, oyster, parts, pet subject,
   potential, power, powers, practice, profession, pursuit,
   qualification, racket, specialism, speciality, specialization,
   specialty, strong flair, strong point, style, talent, talents,
   technicality, the goods, the stuff, thing, trade, type, vocation,
   walk, walk of life, way, weakness, what it takes, work