without beginning or end; lasting forever; always existing ( opposed to temporal )

eternal life.

perpetual; ceaseless; endless

eternal quarreling; eternal chatter.

enduring; immutable

eternal principles.

Metaphysics . existing outside all relations of time; not subject to change.

something that is eternal.

the Eternal, God.

noun

eternality , infinity , perpetuity , sempiternity , ceaselessness , eternity , everlastingness , world without end