delusional

[ dih-loo-zhuh-nl ]
/ dɪˈlu ʒə nl /

adjective

having false or unrealistic beliefs or opinions: Senators who think they will get agreement on a comprehensive tax bill are delusional.
Psychiatry. maintaining fixed false beliefs even when confronted with facts, usually as a result of mental illness: He was so delusional and paranoid that he thought everybody was conspiring against him.
Sometimes de·lu·sion·ar·y.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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