What does "tabula" mean?

Tabula: (Zoöl.) One of the transverse plants found in the calicles of certain corals and hydroids. Tabula rasa ( Etym: [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.