ob ‧ sess /əbˈses/ BrE AmE verb
[ Date: 1500-1600 ; Language: Latin ; Origin: past participle of obsidere 'to besiege' ]
1 . [transitive usually passive] if something or someone obsesses you, you think or worry about them all the time and you cannot think about anything else – used to show disapproval
be obsessed by/with something/somebody
A lot of young girls are obsessed by their weight.
Jody’s been obsessed with some lifeguard for months.
2 . be obsessing about/over something/somebody informal to think about something or someone much more than is necessary or sensible:
Stop obsessing about your hair. It’s fine.