The Collaborative International Dictionary of English v.0.48:
Miller \Mill"er\ (m[i^]l"[~e]r), n.
   1. One who keeps or attends a flour mill or gristmill.
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   2. A milling machine.
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   3. (Zool.)
      (a) A moth or lepidopterous insect; -- so called because
          the wings appear as if covered with white dust or
          powder, like a miller's clothes. Called also moth
          miller.
      (b) The eagle ray.
      (c) The hen harrier. [Prov. Eng.]
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   Miller's thumb. (Zool.)
      (a) A small fresh-water fish of the genus Uranidea
          (formerly Cottus), as the European species
          (Uranidea gobio), and the American (Uranidea
          gracilis); -- called also bullhead.
      (b) A small bird, as the gold-crest, chiff-chaff, and
          long-tailed tit. [Prov. Eng.]
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The Collaborative International Dictionary of English v.0.48:
Bullhead \Bull"head`\, n.
   1. (Zool.)
      (a) A fresh-water fish of many species, of the genus
          Uranidea, esp. Uranidea gobio of Europe, and
          Uranidea Richardsoni of the United States; -- called
          also miller's thumb.
      (b) In America, several species of Amiurus; -- called
          also catfish, horned pout, and bullpout.
      (c) A marine fish of the genus Cottus; the sculpin.
          [1913 Webster]
   2. (Zool.)
      (a) The black-bellied plover (Squatarola helvetica); --
          called also beetlehead.
      (b) The golden plover.
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   3. A stupid fellow; a lubber. [Colloq.] --Jonson.
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   4. (Zool.) A small black water insect. --E. Phillips.
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   Bullhead whiting (Zool.), the kingfish of Florida
      (Menticirrus alburnus).
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