S: (n) eon, aeon (the longest division of geological time)
S: (n) period, geological period (a unit of geological time during which a system of rocks formed) "ganoid fishes swarmed during the earlier geological periods"
S: (n) era, geological era (a major division of geological time; an era is usually divided into two or more periods)
S: (n) epoch (a unit of geological time that is a subdivision of a period and is itself divided into ages)
S: (n) Gnosticism (a religious orientation advocating gnosis as the way to release a person's spiritual element; considered heresy by Christian churches)