Open English Wordnet
Adjectives
(a)eonian, aeonianof or relating to a geological eon (longer than an era) (s)ageless, aeonian, eonian, eternal, everlasting, perpetual, unending, unceasingcontinuing forever or indefinitely“the ageless themes of love and revenge”,
“eternal truths”,
“life everlasting”,
“hell's perpetual fires”,
“the unending bliss of heaven”