The Collaborative International Dictionary of English v.0.48:

Monk \Monk\, n. [AS. munuc, munec, munc, L. monachus, Gr. ?, fr.
   mo`nos alone. Cf. Monachism.]
   1. A man who retires from the ordinary temporal concerns of
      the world, and devotes himself to religion; one of a
      religious community of men inhabiting a monastery, and
      bound by vows to a life of chastity, obedience, and
      poverty. "A monk out of his cloister." --Chaucer.
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            Monks in some respects agree with regulars, as in
            the substantial vows of religion; but in other
            respects monks and regulars differ; for that
            regulars, vows excepted, are not tied up to so
            strict a rule of life as monks are.   --Ayliffe.
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   2. (Print.) A blotch or spot of ink on a printed page, caused
      by the ink not being properly distributed. It is
      distinguished from a friar, or white spot caused by a
      deficiency of ink.
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   3. A piece of tinder made of agaric, used in firing the
      powder hose or train of a mine.
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   4. (Zool.)
      (a) A South American monkey (Pithecia monachus); also
          applied to other species, as Cebus xanthocephalus.
      (b) The European bullfinch.
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   Monk bat (Zool.), a South American and West Indian bat
      (Molossus nasutus); -- so called because the males live
      in communities by themselves.

   Monk bird(Zool.), the friar bird.

   Monk seal (Zool.), a species of seal (Monachus
      albiventer) inhabiting the Black Sea, the Mediterranean
      Sea, and the adjacent parts of the Atlantic.

   Monk's rhubarb (Bot.), a kind of dock; -- also called
      patience (Rumex Patientia).
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The Collaborative International Dictionary of English v.0.48:

Rhubarb \Rhu"barb\, n. [F. rhubarbe, OF. rubarbe, rheubarbe,
   reubarbare, reobarbe, LL. rheubarbarum for rheum barbarum,
   Gr. ??? (and ??) rhubarb, from the river Rha (the Volga) on
   whose banks it grew. Originally, therefore, it was the
   barbarian plant from the Rha. Cf. Barbarous,
   Rhaponticine.]
   1. (Bot.) The name of several large perennial herbs of the
      genus Rheum and order Polygonaceae.
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   2. The large and fleshy leafstalks of Rheum Rhaponticum and
      other species of the same genus. They are pleasantly acid,
      and are used in cookery. Called also pieplant.
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   3. (Med.) The root of several species of Rheum, used much
      as a cathartic medicine.
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   Monk's rhubarb. (Bot.) See under Monk.

   Turkey rhubarb (Med.), the roots of Rheum Emodi.
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