perpetuity

noun

1. (uncountable)The quality or state of being perpetual; endless duration; uninterrupted existence.

   “Mr. Waller adds that when the railway was authorised in 1897, one of the clauses of the Act authorising the transfer of the line to the North British Railway provided that that company should work it in perpetuity, and it was this clause that caused the interim interdict to be granted.”

   “The gnomic belief that the world is conditioned by love is no idle apothegm. Love, as the instrument of creative agencies and cosmic perpetuity, is no banausic conception.”

2. (countable)Something that is perpetual.
3. (countable)A limitation intended to be unalterable and of indefinite duration; a disposition of property which attempts to make it inalienable beyond certain limits fixed or conceived as being fixed by the general law.
4. (countable)An annuity in which the periodic payments begin on a fixed date and continue indefinitely.