eternity

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Time without beginning or end; infinite time.
2. n. The state or quality of being eternal.
3. n. The timeless state following death.
4. n. The afterlife; immortality.
5. n. A very long or seemingly endless time: waited in the dentist's office for an eternity.

Century Dictionary and Cyclopedia

1. n. The condition or quality of being eternal. Infinite duration or continuance, or existence without beginning or end.
2. n. The state of things in which the flow of time has ceased.
3. n. Existence outside of the relations of time.
4. n. The state or condition of existence preceding life, or subsequent to death.
5. n. 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.

Wiktionary

1. n. uncountable Existence without end, infinite time.
2. n. uncountable, philosophy Existence outside of time.
3. n. countable A period of time which extends infinitely far into the future.
4. n. The remainder of time that elapses after death.
5. n. informal, hyperbolic A comparatively long time.

GNU Webster's 1913

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

WordNet 3.0

1. n. time without end
2. n. a seemingly endless time interval (waiting)
3. n. a state of eternal existence believed in some religions to characterize the afterlife