The Collaborative International Dictionary of English v.0.48:

Tabula \Tab"u*la\, n.; pl. Tabulae. [L.]
   1. A table; a tablet.
      [1913 Webster]

   2. (Zool.) One of the transverse plants found in the calicles
      of certain corals and hydroids.
      [1913 Webster]

   Tabula rasa[L.], a smoothed tablet; hence, figuratively,
      the mind in its earliest state, before receiving
      impressions from without; -- a term used by Hobbes, Locke,
      and others, in maintaining a theory opposed to the
      doctrine of innate ideas.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tabula rasa
    n 1: a young mind not yet affected by experience (according to
         John Locke)
    2: an opportunity to start over without prejudice [syn: fresh
       start, clean slate, tabula rasa]

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "tabula rasa":
   agnosticism, blank, blank mind, blankmindedness, blankness,
   bloodless revolution, bouleversement, breakdown, breakup,
   callowness, calm of mind, cataclysm, catastrophe, clean slate,
   clean sweep, computer revolution, convulsion, counterrevolution,
   debacle, emptiness of mind, empty space, empty-headedness,
   fallow mind, fatuity, foolishness, greenhornism, greenness,
   hiatus of learning, ignorance, ignorantism, ignorantness, inanity,
   inexperience, innocence, know-nothingism, knowledge-gap,
   lack of information, mental blankness, nescience, nirvana, nothing,
   nothingness, oblivion, obscurantism, overthrow, overturn,
   palace revolution, passivity, quietism, radical change, rawness,
   revolt, revolution, revolutionary war, revulsion, simpleness,
   simplicity, spasm, striking alteration, subversion,
   sweeping change, technological revolution, thoughtfreeness,
   thoughtlessness, total change, tranquillity, transilience,
   unacquaintance, unfamiliarity, unintelligence, unknowing,
   unknowingness, unripeness, upset, vacancy, vacuity, vacuousness,
   vacuum, violent change, void