Delirium (noun)

1. A serious mental disorder characterized by confusion, hallucinations, and disordered thinking.
2. A state of wild excitement or confusion.

Origin:

Late middle english: via latin from greek delirion, from delirare "go off the rails" , from de- "away from" + lira "track".

Examples:

1. The patient was diagnosed with delirium after being admitted to the hospital.
2. The fever caused delirium and he couldn't recognize anyone.
3. His delirium was caused by the infection in his brain.
4. The patient's delirium was controlled by sedation and antipsychotic medications.
5. After days of no sleep, he fell into a delirium and started talking to himself.