de·lir·i·um (dĭ-lîr'ē-əm) n.
pl.de·lir·i·ums or de·lir·i·a (-ē-ə)
A temporary state of mental confusion and fluctuating consciousness resulting from high fever, intoxication, shock, or other causes. It is characterized by anxiety, disorientation, hallucinations, delusions, and incoherent speech.
A state of uncontrolled excitement or emotion: sports fans in delirium after their team's victory.
[Latin dēlīrium, from dēlīrāre, to be deranged : dē-, de- + līra, furrow; see leis-1 in Indo-European roots.] de·lir'i·ant adj.