Main Entry: ob·ses·sion

Pronunciation: \äb-ˈsesh-ən, əb-\

Function: noun

: a persistent disturbing preoccupation with an often unreasonable idea or feeling ; also : something that causes such preoccupation—compare compulsion, phobia

—ob·ses·sion·al \-ˈsesh-nəl, -ən-^əl\ adjective