From Longman Dictionary of Contemporary Englishimperishableim‧per‧ish‧a‧ble /ɪmˈperɪʃəbəl/ adjective formal LONG TIMEexisting or continuing for a long time or forever a set of imperishable truths
Examples from the Corpus
imperishable• What is sown is perishable, what is raised is imperishable.• Your name will be imperishable if you do this thing in the name of peace.• And is his love so imperishable that, when others deal treacherously with us, he never fails to be loyal?• If the subject-matter of management was a set of imperishable truths, the answer would be no. 