Definition of "delusional"

Morgan could not remember the last time he had heard his first name used, and he had not even been aware that Captain Jackson knew it. Regardless, he could not reply; he was sure he must be delusional. He had lost too much blood […]

2009, Robert M. Cossel, Master of the Strings, page 57

Delusional jealousy […] A delusional belief that one's partner is being unfaithful. This can occur as part of a wider psychotic illness, secondary to organic brain damage (e.g. following the 'punch drunk syndrome' in boxers), […]

2009, David M. Semple, Roger Smyth, Oxford Handbook of Psychiatry, page 87

But of course, that excludes the narcissistic delusionals, the deliberate frauds, and the pathological cases of multiple personality. They are all out there in New Age Land, and it's a jungle!

2005, Laura Knight-Jadczyk, The High Strangeness of Dimensions, Densities, and the Process of Alien Abduction