The Collaborative International Dictionary of English v.0.48:

Unstudied \Unstudied\
   See studied.

The Collaborative International Dictionary of English v.0.48:

Unstudied \Un*stud"ied\, a.
   1. Not studied; not acquired by study; unlabored; natural.
      [1913 Webster]

   2. Not skilled; unversed; -- followed by in.
      [1913 Webster]

   3. Not spent in study. [Obs.] "To cloak the defects of their
      unstudied years." --Milton.
      [1913 Webster]
      [1913 Webster]

WordNet (r) 3.0 (2006):

unstudied
    adj 1: not by design or artifice; unforced and impromptu; "an
           air of unstudied spontaneous utterance is apt to be
           painstakingly achieved"; "simple unstudied charm" [syn:
           unstudied, uncontrived] [ant: studied]
    2: lacking knowledge gained by study often in a particular
       field; "is unstudied in Latin as he is in may other matters"

Moby Thesaurus II by Grady Ward, 1.0:

112 Moby Thesaurus words for "unstudied":
   Bohemian, ad-lib, affable, artless, automatic, casual,
   caught napping, caught off balance, caught short, colloquial,
   common, conversational, cordial, degage, easy, easygoing, everyday,
   extemporaneous, extemporary, extempore, extemporized, familiar,
   folksy, free and easy, gracious, gut, haphazard, hasty, haymish,
   homely, homey, ill-advised, ill-considered, ill-devised, impromptu,
   improvised, inadvertent, indeliberate, informal, ingenuous,
   involuntary, irregular, loose, makeshift, naive, natural,
   nonstandard, offhand, offhanded, plain, precipitate, reflex,
   reflexive, relaxed, rough-and-ready, simple, snap, sociable,
   spoken, spontaneous, spur-of-the-moment, substandard, surprised,
   taken aback, taken by surprise, taken unawares, tripped up,
   unadvised, unaffected, unarranged, unartificial, unassuming,
   unbegun, uncalculated, unceremonious, unconcocted, unconscious,
   unconsidered, unconstrained, uncontrived, unconventional,
   undeliberate, undeliberated, undesigned, undevised, uneducated,
   unexamined, unexplored, unhatched, unintended, unintentional,
   unliterary, unmade, unmanufactured, unmeditated, unofficial,
   unorganized, unplanned, unpremeditated, unprepared, unprimed,
   unready, unrehearsed, unscanned, unschooled, unsearched, unsifted,
   unsophisticated, untutored, unweighed, unwilled, vernacular