(YORISHIRO) An object which attracts divine spirits (souls) or which acts as a media through which these spirits manifest themselves. In episode 26', Kouzou Fuyutsuki refers to Eva-01 as a "Medium" (Well of Souls) when SEELE uses it to create the Tree of Life.

Source: The End of Evangelion : Glossary contained within The End of Evangelion - Theatrical Program.