The Collaborative International Dictionary of English v.0.48:

Canvass \Can"vass\, v. t. [imp. & p. p. canvassed; p. pr. &
   vb. n. Canvassing.] [OF. Canabasser to examine curiously,
   to search or sift out; properly, to sift through canvas. See
   Canvas, n.]
   1. To sift; to strain; to examine thoroughly; to scrutinize;
      as, to canvass the votes cast at an election; to canvass a
      district with reference to its probable vote.
      [1913 Webster]

            I have made careful search on all hands, and
            canvassed the matter with all possible diligence.
                                                  --Woodward.
      [1913 Webster]

   2. To examine by discussion; to debate.
      [1913 Webster]

            An opinion that we are likely soon to canvass. --Sir
                                                  W. Hamilton.
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   3. To go through, with personal solicitation or public
      addresses; as, to canvass a district for votes; to canvass
      a city for subscriptions.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Canvass \Can"vass\, v. i.
   To search thoroughly; to engage in solicitation by traversing
   a district; as, to canvass for subscriptions or for votes; to
   canvass for a book, a publisher, or in behalf of a charity;
   -- commonly followed by for.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Canvass \Can"vass\, n.
   1. Close inspection; careful review for verification; as, a
      canvass of votes. --Bacon.
      [1913 Webster]

   2. Examination in the way of discussion or debate.
      [1913 Webster]

   3. Search; exploration; solicitation; systematic effort to
      obtain votes, subscribers, etc.
      [1913 Webster]

            No previous canvass was made for me.  --Burke.
      [1913 Webster]

WordNet (r) 3.0 (2006):

canvass
    n 1: the setting for a narrative or fictional or dramatic
         account; "the crowded canvas of history"; "the movie
         demanded a dramatic canvas of sound" [syn: canvas,
         canvass]
    2: an inquiry into public opinion conducted by interviewing a
       random sample of people [syn: poll, opinion poll, public
       opinion poll, canvass]
    3: a large piece of fabric (usually canvas fabric) by means of
       which wind is used to propel a sailing vessel [syn: sail,
       canvas, canvass, sheet]
    4: a tent made of canvas fabric [syn: canvas tent, canvas,
       canvass]
    5: an oil painting on canvas fabric [syn: canvas, canvass]
    6: the mat that forms the floor of the ring in which boxers or
       professional wrestlers compete; "the boxer picked himself up
       off the canvas" [syn: canvas, canvass]
    7: a heavy, closely woven fabric (used for clothing or chairs or
       sails or tents) [syn: canvas, canvass]
    v 1: get the opinions (of people) by asking specific questions
         [syn: poll, canvass, canvas]
    2: solicit votes from potential voters in an electoral campaign
       [syn: canvass, canvas]
    3: consider in detail and subject to an analysis in order to
       discover essential features or meaning; "analyze a sonnet by
       Shakespeare"; "analyze the evidence in a criminal trial";
       "analyze your real motives" [syn: analyze, analyse,
       study, examine, canvass, canvas]