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]