venture -- (any venturesome undertaking especially one with an uncertain outcome)
speculation, venture -- (an investment that is very risky but could yield great profits; "he knew the stock was a speculation when he bought it")
venture -- (a commercial undertaking that risks a loss but promises a profit)
Overview of verb venture
The verb venture has 3 senses
venture, embark -- (proceed somewhere despite the risk of possible dangers; "We ventured into the world of high-tech and bought a supercomputer")
guess, venture, pretend, hazard -- (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")