Nonchalant

nonchalant
    adj 1: marked by blithe unconcern; "an ability to interest
           casual students"; "showed a casual disregard for cold
           weather"; "an utterly insouciant financial policy"; "an
           elegantly insouciant manner"; "drove his car with
           nonchalant abandon"; "was polite in a teasing nonchalant
           manner" [syn: {casual}, {insouciant}, {nonchalant}]
    

Nonchalant \Non`cha`lant"\, a. [F., fr. non not (L. non) +
   chaloir to concern one's self for, fr. L. calere to be warm,
   to be inflamed with desire, to be troubled. See {Non-}, and
   {Caldron}.]
   Indifferent; careless; cool.
   [1913 Webster]
    

92 Moby Thesaurus words for "nonchalant":
      Laodicean, Olympian, aloof, apathetic, at ease, ataractic,
      benumbed, blah, blase, calm, careless, casual, cheerful, collected,
      comatose, composed, cool, degage, desensitized, detached,
      devil-may-care, disinterested, dispassionate, disregardful,
      distant, dull, easy, easygoing, effortless, free and easy, glad,
      happy-go-lucky, heartless, hebetudinous, heedless, hopeless,
      imperturbable, in a stupor, inattentive, incurious, indifferent,
      inexcitable, insouciant, lackadaisical, languid, lethargic, light,
      lighthearted, listless, mindless, negligent, numb, numbed, offhand,
      passive, perfunctory, phlegmatic, pluckless, pococurante, reckless,
      regardless, relaxed, resigned, slack, sluggish, smooth, soporific,
      spiritless, spunkless, stoic, stupefied, supine, together, torpid,
      turned-off, unanxious, uncaring, unconcerned, undiscriminating,
      undisturbed, unemotional, unenthusiastic, unexcitable, unexcited,
      unflappable, uninterested, unmindful, unperturbed, unruffled,
      unsolicitous, untroubled, withdrawn