the quality or state of being perpetual; as, the perpetuity of laws.-something that is perpetual.-endless time.-the number of years in which the simple interest of any sum becomes equal to the principal.-the number of years' purchase to be given for an annuity to continue forever.-a perpetual annuity.-duration without limitations as to time.-the quality or condition of an estate by which it becomes inalienable, either perpetually or for a very long period; also, the estate itself so modified or perpetuated.