take upon oneself; act presumptuously, without permission
a challenge to do something dangerous or foolhardy
challenge
to be courageous enough to try or do something
an investment that is very risky but could yield great profits
proceed somewhere despite the risk of possible dangers
put at risk
put forward, of a guess, in spite of possible refutation
a commercial undertaking that risks a loss but promises a profit
any venturesome undertaking especially one with an uncertain outcome
