The Collaborative International Dictionary of English v.0.48:

Wharf \Wharf\, n.; pl. Wharfsor Wharves. [AS. hwerf, hwearf,
   a returning, a change, from hweorfan to turn, turn about, go
   about; akin to D. werf a wharf, G. werft, Sw. varf a
   shipbuilder's yard, Dan. verft wharf, dockyard, G. werben to
   enlist, to engage, woo, OHG. werban to turn about, go about,
   be active or occupied, Icel. hverfa to turn, Goth.
   hwa['i]rban, hwarb[=o]n, to walk. Cf. Whirl.]
   [1913 Webster]
   1. A structure or platform of timber, masonry, iron, earth,
      or other material, built on the shore of a harbor, river,
      canal, or the like, and usually extending from the shore
      to deep water, so that vessels may lie close alongside to
      receive and discharge cargo, passengers, etc.; a quay; a
      pier.
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            Commerce pushes its wharves into the sea.
                                                  --Bancroft.
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            Out upon the wharfs they came,
            Knight and burgher, lord and dame.    --Tennyson.
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   Note: The plural of this word is generally written wharves in
         the United States, and wharfs in England; but many
         recent English writers use wharves.
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   2. [AS. hwearf.] The bank of a river, or the shore of the
      sea. [Obs.] "The fat weed that roots itself in ease on
      Lethe wharf." --Shak.
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   Wharf boat, a kind of boat moored at the bank of a river,
      and used for a wharf, in places where the height of the
      water is so variable that a fixed wharf would be useless.
      [U. S.] --Bartlett.

   Wharf rat. (Zool.)
      (a) The common brown rat.
      (b) A neglected boy who lives around the wharfs. [Slang]
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WordNet (r) 3.0 (2006):

wharf rat
    n 1: someone who lives near wharves and lives by pilfering from
         ships or warehouses
    2: brown rat that infests wharves