The Collaborative International Dictionary of English v.0.48:

Loggerhead \Log"ger*head`\, n. [Log + head.]
   1. A blockhead; a dunce; a numskull. --Shak. Milton.
      [1913 Webster]

   2. A spherical mass of iron, with a long handle, used to heat
      tar.
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   3. (Naut.) An upright piece of round timber, in a whaleboat,
      over which a turn of the line is taken when it is running
      out too fast. --Ham. Nav. Encyc.
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   4. (Zool.) A very large marine turtle (Thalassochelys
      caretta syn. Thalassochelys caouana), common in the
      warmer parts of the Atlantic Ocean, from Brazil to Cape
      Cod; -- called also logger-headed turtle.
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   5. (Zool.) An American shrike (Lanius Ludovicianus),
      similar to the butcher bird, but smaller. See Shrike.
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   To be at loggerheads, To fall to loggerheads, or To go
   to loggerheads, to quarrel; to be at strife. --L' Estrange.
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The Collaborative International Dictionary of English v.0.48:

butcher bird \butcher bird\, butcher-bird \butcher-bird\,
butcherbird \butcherbird\n.
   1. (Zool.) any species of shrike of the genus Lanius, so
      called because they impale their prey on thorns.
      [1913 Webster + WordNet 1.5]

   2. (Zool.) large carnivorous Australian bird with the
      shrikelike habit of impaling prey on thorns.
      [WordNet 1.5]

   Note: The Lanius excubitor is the common butcher bird of
         Europe. In England, the bearded tit is sometimes called
         the lesser butcher bird. The American species are
         Lanius borealis, or northern butcher bird, and
         Lanius Ludovicianus or loggerhead shrike. The name
         butcher bird is derived from its habit of suspending
         its prey impaled upon thorns, after killing it.
         [1913 Webster]