par ‧ a ‧ noi ‧ a /ˌpærəˈnɔɪə/ BrE AmE noun [uncountable]
[ Date: 1800-1900 ; Language: Greek ; Origin: 'mental illness' , from para- ( ⇨ ↑ para- ) + nous 'mind' ]
1 . an unreasonable belief that you cannot trust other people, or that they are trying to harm you or have a bad opinion of you
2 . medical a mental illness that makes someone believe that they are very important and that people hate them and are trying to harm them