n.1 an acutely disordered state of mind involving incoherent speech, hallucinations, and frenzied excitement, occurring in metabolic disorders, intoxication, fever, etc.
2 great excitement, ecstasy.
Phrases and idioms:
delirium tremens a psychosis of chronic alcoholism involving tremors and hallucinations.
Etymology: L f. delirare be deranged (as DE-, lira ridge between furrows)