any venturesome undertaking especially one with an uncertain outcome

an investment that is very risky but could yield great profits

同义词：speculation

a commercial undertaking that risks a loss but promises a profit

proceed somewhere despite the risk of possible dangers

同义词：embark

put forward, of a guess, in spite of possible refutation

同义词：guess??/??pretend??/??hazard

put at risk

同义词：hazard??/??adventure??/??stake??/??jeopardize