eternity

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Time without beginning or end; infinite time.
• noun The state or quality of being eternal.
• noun The timeless state following death.
• noun The afterlife; immortality.
• noun A very long or seemingly endless time.

from The Century Dictionary.

• noun The condition or quality of being eternal.
• noun The state of things in which the flow of time has ceased.
• noun Existence outside of the relations of time.
• noun The state or condition of existence preceding life, or subsequent to death.
• noun Indefinite duration of time or vast extent of space; anything that seems endless; endless round: as, an eternity of suspense; the great desert with its eternity of sand.

from the GNU version of the Collaborative International Dictionary of English.

• noun Infinite duration, without beginning in the past or end in the future; also, duration without end in the future; endless time.
• noun Condition which begins at death; immortality.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun uncountable Existence without end, infinite time.
• noun uncountable, philosophy Existence outside of time.
• noun countable A period of time which extends infinitely far into the future.
• noun The remainder of time that elapses after death.
• noun informal, hyperbolic A comparatively long time.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun time without end
• noun a seemingly endless time interval (waiting)
• noun a state of eternal existence believed in some religions to characterize the afterlife