The Collaborative International Dictionary of English v.0.48:

Venture \Ven"ture\, v. t.
   1. To expose to hazard; to risk; to hazard; as, to venture
      one's person in a balloon.
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            I am afraid; and yet I'll venture it. --Shak.
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   2. To put or send on a venture or chance; as, to venture a
      horse to the West Indies.
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   3. To confide in; to rely on; to trust. [R.]
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            A man would be well enough pleased to buy silks of
            one whom he would not venture to feel his pulse.
                                                  --Addison.
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The Collaborative International Dictionary of English v.0.48:

Venture \Ven"ture\, v. i. [imp. & p. p. Ventured; p. pr. & vb.
   n. Venturing.]
   1. To hazard one's self; to have the courage or presumption
      to do, undertake, or say something; to dare. --Bunyan.
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   2. To make a venture; to run a hazard or risk; to take the
      chances.
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            Who freights a ship to venture on the seas. --J.
                                                  Dryden, Jr.
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   To venture at, or To venture on or To venture upon, to
      dare to engage in; to attempt without any certainty of
      success; as, it is rash to venture upon such a project.
      "When I venture at the comic style." --Waller.
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The Collaborative International Dictionary of English v.0.48:

Venture \Ven"ture\ (?; 135), n. [Aphetic form of OE. aventure.
   See Adventure.]
   1. An undertaking of chance or danger; the risking of
      something upon an event which can not be foreseen with
      certainty; a hazard; a risk; a speculation.
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            I, in this venture, double gains pursue. --Dryden.
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   2. An event that is not, or can not be, foreseen; an
      accident; chance; hap; contingency; luck. --Bacon.
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   3. The thing put to hazard; a stake; a risk; especially,
      something sent to sea in trade.
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            My ventures are not in one bottom trusted. --Shak.
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   At a venture, at hazard; without seeing the end or mark;
      without foreseeing the issue; at random.
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            A certain man drew a bow at a venture. --1 Kings
                                                  xxii. 34.
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            A bargain at a venture made.          --Hudibras.
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   Note: The phrase at a venture was originally at aventure,
         that is, at adventure.
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WordNet (r) 3.0 (2006):

venture
    n 1: any venturesome undertaking especially one with an
         uncertain outcome
    2: an investment that is very risky but could yield great
       profits; "he knew the stock was a speculation when he bought
       it" [syn: speculation, venture]
    3: a commercial undertaking that risks a loss but promises a
       profit
    v 1: proceed somewhere despite the risk of possible dangers; "We
         ventured into the world of high-tech and bought a
         supercomputer" [syn: venture, embark]
    2: put forward, of a guess, in spite of possible refutation; "I
       am guessing that the price of real estate will rise again";
       "I cannot pretend to say that you are wrong" [syn: guess,
       venture, pretend, hazard]
    3: put at risk; "I will stake my good reputation for this" [syn:
       venture, hazard, adventure, stake, jeopardize]

Moby Thesaurus II by Grady Ward, 1.0:

186 Moby Thesaurus words for "venture":
   accept, advance, adventure, affair, agiotage, approach, arbitrage,
   assay, assume, attack, attempt, banter, be a man, be caught short,
   be short, beard, belong, bet, brave, broach, bucket, bucketshop,
   buckle to, business, buy in, buy into, buying in, calculated risk,
   challenge, chance, chance it, commitment, contract, crack, dare,
   daresay, deal, defy, deposit margin, effort, embark in,
   embark upon, emprise, endanger, endeavor, engage, engage in,
   engagement, enter on, enter upon, enterprise, equity capital,
   essay, experiment, exploit, expose, face, fall into, fall to, feat,
   financier, flier, fling, flutter, fortune, front, gamble,
   gamble on, gest, get under way, go about, go at, go in for,
   go into, go long, go upon, have at, have the guts, have the nerve,
   hazard, hold on, imperil, invest, invest in, investment, jeopard,
   jeopardize, jeopardy, launch forth, launch into, lay about,
   lay open, lay out money, lift a finger, liquidation, luck,
   make a killing, make a scoop, make an attempt, make an effort,
   make an investment, make bold, make bold to, make free, margin up,
   miss the market, move into, obligation, offer, operate, operation,
   outdare, outface, overstay the market, peril, pitch into, place,
   plan, play, play the market, plow back into, plunge, plunge into,
   presume, pretend, prime investment, proceed to, proffer,
   profit taking, program, project, proposition, put, put down,
   put forward, pyramid, reinvest, rely on fortune, risk, round trade,
   run a chance, run the risk, scalp, scalping, scoop the market,
   set about, set at, set at hazard, set forward, set going, set to,
   sink, sink money in, speculate, speculation, spot sale, stag,
   stag the market, stake, stockjobbery, stockjobbing, tackle,
   take a chance, take a flier, take chances, take on,
   take the liberty, take up, task, tempt fortune, tender,
   trade on margin, trust to chance, try, try the chance, turn,
   turn to, uncertainty, undertake, undertaking, venture capital,
   venture on, venture upon, volunteer, wager, work