eternal

Concise Oxford English Dictionary © 2008 Oxford University Press:
eternal /ɪˈtəːn(ə)l, iː-/

▶adjective

• 1 lasting or existing forever.

  ■ informal tediously lengthy or persistent.

• 2 valid for all time; essentially unchanging: eternal truths.

• 3 (the Eternal) an everlasting or universal spirit, as represented by God.

– phrases
the Eternal City the city of Rome.
eternal triangle a relationship between three people involving sexual rivalry.

– derivatives
eternality /ɪˌtəːˈnalɪti, iː-/ noun,
eternalize (or eternalise) verb,
eternally adverb,
eternalness noun.

– origin ME: via OFr. from late L. aeternalis, from L. aeternus, from aevum ‘age’.