Cetra: Also known as the Ancients, the Cetra look pretty much like human beings, but they have extraordinary magical skills. They existed thousands of years ago and are believed to be extinct.
Forgotten Capital: A large abandoned city believed to have once been the capital city of the Ancients.
Highwind: A huge airship originally owned by the Shinra Corporation. Cloud and his companions stole it during one of their tussles with Shinra.
Jenova: A living being preserved for 2000 years and believed to be a Cetra.
Lifestream: The lifeblood of the planet. It is located in the core of the planet and is what allows it to maintain it's natural balance. Though it is considered as the source of life, the tremendous energy that it harbors is hazardous to biological beings. The lifestream also contains all the knowledge that the planet has accumulated during the course of it's life.
Magical Terms (Fire, Fire2 etc.): Materia has different levels of abilities depending on which enemies it has been used on. The higher the number next to the name of the magical attack, the more powerful it is.
Mako Energy: The processed form of the planet's spirit energy. The Shinra Corporation invented Mako Reactors to harness this energy and it replaced all other sources of fuel. Though Mako Energy is powerful, when used it does not return to the planet and is lost forever.
Masamune: Sephiroth's sword. It is long, sharp with only one edge. It looks very much like a Japanese sword. It possesses unknown powers in the hands of Sephiroth.
Materia: The crystallized form of Mako Energy containing the knowledge of the ancients. Materia are used in combat, granting the user enhanced or new abilities. Materia has different properties depending on its color. Green is magic materia. Blue is support materia. Yellow is command materia. Red is summon materia etc.
Shinra: A corporation specializing in manufacturing weapons and seeking to control the world.
Sister Ray: A huge cannon approximately the size of a five story building used by Shinra in strategic assaults. The name was given by Scarlet, an influential woman within Shinra.
SOLDIER: Shinra's elite task force. Only the finest men are accepted. Members of SOLDIER or those aspiring to be one are infused with Mako Energy giving their eyes a pale blue color.
Spirit Energy: The energy that all living things possess. When a creature dies, it's spirit energy is returned to the planet through the lifestream, to be reused when a new life is born. If a planet's spirit energy is depleted, it would crumble and plummet into oblivion.
Weapon: The planet's natural antibodies believed to have originated from the Lifestream. Once awakened, Weapon's only goal is to destroy whatever is threatening the life of the planet.