to dominate or preoccupy the thoughts, feelings, or desires of (a person); beset, trouble, or haunt persistently or abnormally: Suspicion obsessed him.
verb (used without object)
2.
to think about something unceasingly or persistently; dwell obsessively upon something.
Origin: 1495–1505; < Latinobsessus, past participle of obsidēre to occupy, frequent, besiege, equivalent to ob-ob- + -sid(ēre) combining form of sedēre to sit
c.1500, "to besiege," from L. obsessus, pp. of obsidere "besiege, occupy," lit. "sit opposite to," from ob "against" + sedere "sit." Of evil spirits, "to haunt," is from 1530s.