(formal) everlasting; endless

(philosophy, theology) Existence within time but infinitely into the future, as opposed to eternity, understood as existence outside time. / (literary) Eternity; a seemingly everlasting period of time.

Everlasting, eternal. / (philosophy) Everlasting, that is, having infinite temporal duration (as opposed to eternal: outside time and thus lacking temporal duration altogether).

In a sempiternal manner; eternally. / (philosophy) in an everlasting manner, as to have an infinite temporal duration; as opposed to eternally or timelessly, as to exist outside time

(obsolete, poetic) sempiternal; everlasting