obsessed

UK: /əbˈsɛst/ US: (əb sest′)

WordReference Random House Unabridged Dictionary of American English © 2026

ob•sessed  (əb sest′), adj. 

1. having an obsession (usually fol. by with or by):
   He is obsessed with eliminating guilt.
2. having or displaying signs of an obsession:
   The audiophile entered the record store wearing an obsessed smile.

• obsess + -ed² 1835–45

WordReference Random House Learner's Dictionary of American English © 2026

ob•sess /əbˈsɛs/   v. 

1. to dominate the thoughts of;
   preoccupy:
   [~ + object] Revenge obsessed him.
2. to think about something without stopping:
   [no object] He obsessed about his old girlfriend for years.

See -sess-.

WordReference Random House Unabridged Dictionary of American English © 2026

ob•sess  (əb ses′), v.t. 

1. to dominate or preoccupy the thoughts, feelings, or desires of (a person);
   beset, trouble, or haunt persistently or abnormally:
   Suspicion obsessed him.

v.i. 

2. to think about something unceasingly or persistently;
   dwell obsessively upon something.

• Latin obsessus, past participle of obsidēre to occupy, frequent, besiege, equivalent. to ob- ob- + -sid(ēre) combining form of sedēre to sit
• 1495–1505

ob•sess′ing•ly, adv. 
ob•ses′sor, n. 
Synonyms

• 1. possess, control, haunt.

Collins Concise English Dictionary © HarperCollins Publishers::

obsess / əbˈsɛs/ verb

1. (tr; when passive, followed by with or by) to preoccupy completely; haunt
2. (intr; usually followed by on or over) to worry neurotically or obsessively; brood

Etymology: 16th Century: from Latin obsessus besieged, past participle of obsidēre, from ob- in front of + sedēre to sit