The Collaborative International Dictionary of English v.0.48:

Untrodden \Untrodden\
   See trodden.

WordNet (r) 3.0 (2006):

untrodden
    adj 1: lacking pathways; "trackless wilderness"; "roadless
           areas" [syn: pathless, roadless, trackless,
           untracked, untrod, untrodden]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "untrodden":
   callow, dewy, ever-new, evergreen, extra, firsthand, fledgling,
   fresh, green, held back, held in reserve, held out, immature,
   imperforate, in abeyance, in hand, intact, maiden, maidenly, mint,
   neoteric, nestling, new, original, pathless, pierceless, pristine,
   put aside, put by, raw, reserve, saved, sempervirent, spare,
   stored, suspended, to spare, trackless, unapplied, unbeaten,
   unconsumed, undeveloped, unemployed, unexercised, unexpended,
   unfledged, unhandled, unperforated, unpierced, unspent, untapped,
   untouched, untried, unused, unutilized, vernal, virgin, virginal,
   waived, wayless, young