plumbago

plumbago
    n 1: used as a lubricant and as a moderator in nuclear reactors
         [syn: {graphite}, {black lead}, {plumbago}]
    2: any plumbaginaceous plant of the genus Plumbago
    

Graphite \Graph"ite\, n. [Gr. gra`fein to write: cf. F.
   graphite. See {Graphic}.] (Min.)
   Native carbon in hexagonal crystals, also foliated or
   granular massive, of black color and metallic luster, and so
   soft as to leave a trace on paper. It is used for pencils
   (improperly called lead pencils), for crucibles, and as a
   lubricator, etc. Often called {plumbago} or {black lead}.
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   {Graphite battery} (Elec.), a voltaic battery consisting of
      zinc and carbon in sulphuric acid, or other exciting
      liquid.
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Plumbago \Plum*ba"go\, n. [L., from plumbum lead.]
   1. (Min.) Same as {Graphite}.
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   2. (Bot.) A genus of herbaceous plants with pretty
      salver-shaped corollas, usually blue or violet; leadwort.
      [1913 Webster] Plumbean