Answer: unending equal payments paid at equal time intervals
Explanation: a perpetuity can be defined as an annuity (a right to receive amounts of money regularly over a certain fixed period, in perpetuity, or, especially, over the remaining life or lives of one or more beneficiary) in which the periodic payments begin on a fixed date and continue indefinitely. Therefore, perpetuity are unending equal payments paid at equal time intervals. An example of a common perpetuity is the preferred stock.