in perpetuity

/ɪn ˈpʌrpəˌtuədi/

In perpetuity means "forever." If you are banned from the library in perpetuity after that one time you stood on a table and played your trumpet, it means that you will never be allowed back.

Using the adverbial phrase in perpetuity is a formal way to say "forever and ever," or "indefinitely," or "until further notice." A truly sustainable form of energy will provide power in perpetuity, and the words of a brilliant, important poet will last in perpetuity. The root is the Latin word perpetuitatem, "uninterrupted duration or continuity,", and it's related to perpetual, or "never ending."

Definitions of in perpetuity

1. adverb

   for life
   “desire happiness in perpetuity”

   “an annuity paid in perpetuity”
2. adverb

   for an indefinitely long time
   “bequeathed to the nation in perpetuity”