paranoia
//ˌpær.əˈnɔɪ.ə//
Noun
1
A mental condition characterized by delusions of persecution, unwarranted jealousy, or exaggerated self-importance.
The psychiatrist diagnosed the patient with paranoia after observing persistent delusions of persecution.
2
Extreme, irrational distrust or suspicion of others.
His paranoia made him believe that all his coworkers were plotting against him.