“a mental state in which you are confused and not able to think or speak clearly usually because of fever or some other illness [. . .]. an acute mental disturbance characterized by confused thinking and disrupted attention usually accompanied by disordered speech and hallucinations.”
“Examples of DELIRIUM: In her delirium, nothing she said made any sense.
Better still, from the OED:
“1. A disordered state of the mental faculties resulting from disturbance of the functions of the brain, and characterized by incoherent speech, hallucinations, restlessness, and frenzied or maniacal excitement.”
“2. fig. Uncontrollable excitement or emotion, as of a delirious person; frenzied rapture; wildly absurd thought or speech.”