1. a mental condition characterized by delusions of persecution, grandeur, or reference, often without basis in reality
Usage: clinical/medical term; often capitalized when referring to the specific psychiatric disorder
2. an irrational or excessive fear or distrust of others
Usage: informal usage, less severe than clinical paranoia

Examples

• The patient's paranoia made him believe that strangers were following him everywhere.
• After the argument, she developed a paranoia about what her coworkers were saying behind her back.
• His paranoia about losing his job caused him constant anxiety.
• The documentary explored how paranoia can develop in isolated communities.
• She struggled with paranoia and found it difficult to maintain friendships.
• His paranoia about germs led him to wash his hands dozens of times a day.