internal rate of return

index used to estimate is an investment is worthwhile according to its relation to expected interest during the life of the investment

The internal rate of return (IRR) is a capital budgeting method used by firms to decide whether they should make long-term investments. The IRR is the annualized effective compounded return rate which can be earned on the invested capital, i.e. the yield on the investment.A project is a good investment proposition if its IRR is greater than the rate of return that could be earned by alternative investments (investing in other projects, buying bonds, even putting the money in a bank account). Thus, the IRR should be compared to an alternative cost of capital including an appropriate risk premium.
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Dollar-weighted rate of return. Discount rate at which net present value (N.P.V. ) investment is zero. The rate at which a bond's future cash flows, discounted back to today, equals its price.

the discount rate at which the net present value of an investment is zero.