The Collaborative International Dictionary of English v.0.48:

Grub \Grub\, n.
   1. (Zool.) The larva of an insect, especially of a beetle; --
      called also grubworm. See Illust. of Goldsmith beetle,
      under Goldsmith.
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            Yet your butterfly was a grub.        --Shak.
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   2. A short, thick man; a dwarf. [Obs.] --Carew.
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   3. Victuals; food. [Slang] --Halliwell.
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   Grub ax or Grub axe, a kind of mattock used in grubbing
      up roots, etc.

   Grub breaker. Same as Grub hook (below).

   Grub hoe, a heavy hoe for grubbing.

   Grub hook, a plowlike implement for uprooting stumps,
      breaking roots, etc.

   Grub saw, a handsaw used for sawing marble.

   Grub Street, a street in London (now called Milton
      Street), described by Dr. Johnson as "much inhabited by
      writers of small histories, dictionaries, and temporary
      poems, whence any mean production is called grubstreet."
      As an adjective, suitable to, or resembling the production
      of, Grub Street.
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            I 'd sooner ballads write, and grubstreet lays.
                                                  --Gap.
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WordNet (r) 3.0 (2006):

Grub Street
    n 1: the world of literary hacks