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.
      [1913 Webster]

   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]

Moby Thesaurus II by Grady Ward, 1.0:

205 Moby Thesaurus words for "canvass":
   Australian ballot, Hare system, address, addresses, agitate, air,
   all-out campaign, analyze, angle for, argue, assemblage, assembly,
   autopsy, aye, ballot, bid for, call-up, campaign, campaign button,
   campaign commitments, campaign contribution, campaign fund,
   canvassing, case, cast a ballot, casting vote, census, check,
   check out, check over, check up, check up on, collection,
   colligation, collocation, combination, comment upon, comparison,
   con, concourse, concurrence, conduct a poll, confluence, conflux,
   congregation, consider, consumer research,
   consumer-preference survey, controvert, convergence, corralling,
   counting heads, court, courting, cumulative voting, data-gathering,
   deal with, debate, deciding vote, deliberate, deliberate upon,
   discept, discourse about, discuss, dispute, divide, division, drum,
   electioneer, enfranchisement, examination, examine, exchange views,
   fagot vote, fish for, franchise, gathering, give an examination,
   go into, go over, grass-roots campaign, graveyard vote, hand vote,
   handle, hard-hitting campaign, hurrah campaign, ingathering,
   inquiry, inspect, interview, inventory, investigate, investigation,
   junction, juxtaposition, knock around, list system, look at,
   look for, look over, make a survey, media campaign, mobilization,
   monitor, moot, muster, nay, no, nontransferable vote, observe,
   opinion poll, overhaul, overlook, pass over, pass under review,
   peer at, peruse, plebiscite, plebiscitum, plump, plumper,
   plural vote, poll, polling, pop the question, pore over,
   postmortem, preferential voting, proportional representation,
   proxy, public-opinion poll, question, questionary, questionnaire,
   rap, reason, reason about, reason the point, record vote,
   referendum, representation, review, right to vote, ring doorbells,
   rising vote, rodeo, roundup, run over, sample, say, scan,
   scrutinize, secret ballot, seek, set an examination, show of hands,
   sift, single vote, size, size up, snap vote, solicit,
   solicit votes, solicitation, straw vote, study, stump,
   stump excursion, stump the country, stumping tour, sue, sue for,
   suffrage, suit, survey, take stock of, take the measure,
   take the stump, take up, talk, talk about, talk of, talk over,
   tally, thrash out, thresh out, transferable vote, treat, ventilate,
   vet, viva voce, voice, voice vote, vote, voting, voting right,
   whistle-stop, whistle-stop campaign, woo, wooing, write-in,
   write-in vote, yea, yeas and nays, yes