Ob-sés'sion, n.
(-sĕsh'un), n. [Lat. obsessio, Fr. obsession, Sp. obsesion, It. ossessione. See OBSESS.]
Sense 1. The act of besieging, or the state of being besieged.
Sense 2. The state of a person vexed or besieged by an evil spirit, antecedent to possession. [Obs.]
Whether by obsession, possession, or otherwise, I will not determine. Burton.