obsess

 
Pronunciation: /əbˈsɛs/

verb

[with object]
  • preoccupy or fill the mind of (someone) continually and to a troubling extent: he was obsessed with the idea of revenge I became more and more obsessed by him
  • [no object] be constantly talking or worrying about something: her husband, who is obsessing about the wrong she has done him

Origin:

late Middle English (in the sense 'haunt, possess', referring to an evil spirit): from Latin obsess- 'besieged', from the verb obsidere, from ob- 'opposite' + sedere 'sit'. The current sense dates from the late 19th century