The Collaborative International Dictionary of English v.0.48:

Tablet \Ta"blet\, n. [F. tablette, dim. of table. See Table.]
   1. A small table or flat surface.
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   2. A flat piece of any material on which to write, paint,
      draw, or engrave; also, such a piece containing an
      inscription or a picture.
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   3. Hence, a small picture; a miniature. [Obs.]
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   4. pl. A kind of pocket memorandum book.
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   5. A flattish cake or piece; as, tablets of arsenic were
      formerly worn as a preservative against the plague.
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   6. (Pharm.) A solid kind of electuary or confection, commonly
      made of dry ingredients with sugar, and usually formed
      into little flat squares; -- called also lozenge, and
      troche, especially when of a round or rounded form.
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The Collaborative International Dictionary of English v.0.48:

Troche \Tro"che\ (tr[=o]"k[=e]), n. [Gr. trocho`s anything round
   or circular, a wheel, properly, a runner, fr. tre`chein to
   run. Cf. Trochee.] (Pharm.)
   A medicinal tablet or lozenge; strictly, one of circular
   form.
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WordNet (r) 3.0 (2006):

troche
    n 1: a medicated lozenge used to soothe the throat [syn: cough
         drop, troche, pastille, pastil]