Endless duration; duration for an indefinite period; something perpetual; a sum that will purchase an annuity.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (noun) (n.) (noun)
The state of being everlasting; endless time; something that lasts forever.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (noun) (n.) (noun)
Endless duration; continued and uninterrupted existence for an indefinite period of time; something of which there is no end.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (noun) (n.) (noun)
State of being perpetual: endless duration: duration for an indefinite period: something perpetual: the sum paid for a perpetual annuity.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)
State of being perpetual; endless duration; anything perpetual.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (noun) (n.) (noun)

Usage examples:

Why should Sir Florian make away, in perpetuity with his family property?
- The Eustace Diamonds by Anthony Trollope
Then came the Saxon supremacy under the good King Egfrith, with the spiritual oversight under Saint Cuthbert, to whom and his successors at Lindisfarne were bestowed in perpetuity the city with fifteen miles around it.
- In the Border Country by W. S. (William Shillinglaw) Crockett
She could procure no considerable loans, therefore she has mortgaged no such oppressive taxes as those Great Britain has imposed in perpetuity for payment of interest.
- The Works of the Right Honourable Edmund Burke, Vol. I. (of 12) by Edmund Burke