The Collaborative International Dictionary of English v.0.48:

Thereabout \There"a*bout`\, Thereabouts \There"a*bouts`\, adv.
   [The latter spelling is less proper, but more commonly used.]
   1. Near that place.
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   2. Near that number, degree, or quantity; nearly; as, ten
      men, or thereabouts.
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            Five or six thousand horse . . . or thereabouts.
                                                  --Shak.
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            Some three months since, or thereabout. --Suckling.
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   3. Concerning that; about that. [R.]
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            What will ye dine? I will go thereabout. --Chaucer.
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            They were much perplexed thereabout.  --Luke xxiv.
                                                  4.
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WordNet (r) 3.0 (2006):

thereabout
    adv 1: near that time or date; "come at noon or thereabouts"
           [syn: thereabout, thereabouts]
    2: near that place; "he stayed in London or thereabouts for
       several weeks" [syn: thereabout, thereabouts]