believing in things that do not exist or are not true, such as with having faulty judgment that makes one extremely mistaken;
e.g. Few Americans have the delusional belief that they can escape consequences from this current economic downtown.
(noun)
(psychiatry) a persistent false psychotic belief regarding the self or persons or objects outside the self, that is maintained despite indisputable evidence to the contrary;
e.g. In the hospital she became delusional from the combination of general anesthesia and the strong pain-killers.