verb (used with object)
- 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)
- to think about something unceasingly or persistently; dwell obsessively upon something.
- (tr; when passive, foll by with or by) to preoccupy completely; haunt
- (intr; usually foll by on or over) to worry neurotically or obsessively; brood
v.c.1500, “to besiege,” from Latin obsessus, past participle of obsidere “watch closely; besiege, occupy; stay, remain, abide” literally “sit opposite to,” from ob “against” (see ob-) + sedere “sit” (see sedentary). Of evil spirits, “to haunt,” from 1530s. Psychological sense is 20c. Related: Obsessed; obsessing.