The Collaborative International Dictionary of English v.0.48:

Unseasoned \Un*sea"soned\, a.
   1. Not seasoned.
      [1913 Webster]

   2. Untimely; ill-timed. [Obs.] --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unseasoned
    adj 1: not aged or processed; "unseasoned timber" [ant:
           seasoned]
    2: without salt or seasoning [syn: unsalted, unseasoned]
    3: not tried or tested by experience; "unseasoned artillery
       volunteers"; "still untested in battle"; "an illustrator
       untried in mural painting"; "a young hand at plowing" [syn:
       unseasoned, untested, untried, young]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "unseasoned":
   a novice at, a stranger to, adolescent, at half cock, budding,
   callow, dewy, disaccustomed, fledgling, fresh, green,
   green as grass, growing, half-baked, half-cocked, half-grown,
   ignorant, ill-digested, immature, impubic, inexperienced,
   ingenuous, innocent, intact, juicy, juvenile, minor, naive, new to,
   new-fledged, raw, ripening, rusty, sappy, tender, unaccustomed,
   unaccustomed to, unacquainted with, unadult, unconversant,
   unconversant with, underage, underripe, undeveloped, unexperienced,
   unfamiliar with, unfledged, unformed, ungrown, unhabituated,
   unhardened, uninitiated in, uninured, unlicked, unmatured,
   unmellowed, unpracticed, unpracticed in, unripe, unskilled in,
   untrained, untried, unused, unused to, unversed, unversed in,
   unwonted, vernal, virginal, weaned, young