The Collaborative International Dictionary of English v.0.48:

Unaffected \Un`af*fect"ed\, a.
   1. Not affected or moved; destitute of affection or emotion;
      uninfluenced.
      [1913 Webster]

            A poor, cold, unspirited, unmannered,
            Unhonest, unaffected, undone fool.    --J. Fletcher.
      [1913 Webster]

   2. Free from affectation; plain; simple; natural; real;
      sincere; genuine; as, unaffected sorrow.
      [1913 Webster] -- Un`af*fect"ed*ly, adv. --
      Un`af*fect"ed*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unaffected
    adj 1: undergoing no change when acted upon; "entirely
           unaffected by each other's writings"; "fibers remained
           apparently unaffected by the treatment" [ant: affected]
    2: unaware of or indifferent to; "insensible to the suffering
       around him" [syn: insensible(p), unaffected(p)]
    3: emotionally unmoved; "always appeared completely unmoved and
       imperturbable" [syn: unmoved(p), unaffected, untouched]
       [ant: affected, moved(p), stirred, touched]
    4: free of artificiality; sincere and genuine; "an unaffected
       grace" [ant: affected, unnatural]

Moby Thesaurus II by Grady Ward, 1.0:

224 Moby Thesaurus words for "unaffected":
   Attic, Bohemian, Ciceronian, Spartan, adamant, adamantine,
   aesthetic, affable, arcadian, artistic, artless, ascetic, austere,
   authentic, bald, bare, bona fide, bucolic, candid, card-carrying,
   cast-iron, casual, chaste, choice, classic, clear, common,
   commonplace, cordial, degage, dinkum, direct, dour, dry, dull,
   easy, easygoing, elegant, excellent, familiar, finished, firm,
   flinty, folksy, following the letter, frank, free and easy,
   genuine, good, graceful, gracile, gracious, grim, guileless, hard,
   hard-core, haymish, homely, homespun, homey, honest, honest-to-God,
   immovable, immutable, implacable, impliable, in good taste,
   inartificial, inelastic, inexorable, inflexible, informal,
   ingenuous, intransigent, iron, irreconcilable, irregular, lawful,
   lean, legitimate, lifelike, limpid, literal, loose, lucid, native,
   natural, naturalistic, naturelike, neat, of choice, of quality,
   offhand, offhanded, open, original, pastoral, pellucid,
   perspicuous, plain, plain-speaking, plain-spoken, pleasing,
   polished, prosaic, prosing, prosy, pure, quiet, real, realistic,
   refined, relaxed, relentless, restrained, rightful, rigid,
   rigorous, rock-ribbed, round, rural, rustic, severe, simon-pure,
   simple, simple-speaking, sincere, sober, sociable, spare, stark,
   steely, sterling, stern, stiff, straightforward, subdued,
   sure-enough, tasteful, terse, trim, true to life, true to nature,
   true to reality, unadorned, unadulterated, unalterable, unanimated,
   unartificial, unassumed, unassuming, unbeguileful, unbeguiling,
   unbending, uncalculating, unceremonious, unchangeable, uncolored,
   uncompromising, unconcocted, unconstrained, unconventional,
   uncopied, uncounterfeited, undeceitful, undeceiving, undeceptive,
   understated, undesigning, undisguised, undisguising, undissembling,
   undissimulated, undissimulating, undistorted, unembellished,
   unexaggerated, unfabricated, unfanciful, unfeigned, unfeigning,
   unfictitious, unflattering, ungiving, unimaginative, unimagined,
   unimitated, unimpressed, uninfluenced, uninspired, uninvented,
   unlabored, unmoved, unobtrusive, unofficial, unpoetical,
   unpretended, unpretending, unpretentious, unqualified, unrelenting,
   unromantic, unruffled, unschooled, unsimulated, unsophisticated,
   unspecious, unspoiled, unstirred, unstruck, unstudied, unswayed,
   unsynthetic, untouched, untrimmed, untutored, unvarnished,
   unyielding, verbal, verbatim, veridical, verisimilar, well-chosen,
   word-for-word