If the definition explains the meaning of a word, surely it can't be essential that you should have heard the word before. It is the ostensive definition's business to give it a meaning. Let us then explain the word “tove” by pointing to a pencil and saying “this is tove”. (Insted of “this is tove” I could here have said “this is called ‘tove’”. I point this out to remove, once and for all, the idea that the words of the ostensive definition predicate something of the defined; the confusion between the sentence “this is red”, attributing the colour red to something, and this ostensive definition “this is called ‘red’”.) Now the ostensive definition “this is tove” can be interpreted in all sorts of ways. I will give a few such interpretations and use English words with well established usage. The definition then can be interpreted to mean:–
3.
      “This is a pencil”,
      “This is round”,
      “This is wood”,
      “This is one”,
      “This is hard”, etc. etc.