The Collaborative International Dictionary of English v.0.48:
Delirium \De*lir"i*um\ (d[-e]*l[i^]r"[i^]*[u^]m), n. [L., fr.
delirare to rave, to wander in mind, prop., to go out of the
furrow in plowing; de- + lira furrow, track; perh. akin to G.
geleise track, rut, and E. last to endure.]
1. (Med.) A state in which the thoughts, expressions, and
actions are wild, irregular, and incoherent; mental
aberration; a roving or wandering of the mind, -- usually
dependent on a fever or some other disease, and so
distinguished from mania, or madness.
2. Strong excitement; wild enthusiasm; madness.
The popular delirium [of the French Revolution] at
first caught his enthusiastic mind. --W. Irving.
The delirium of the preceding session (of
Delirium tremens. [L., trembling delirium] (Med.), a
violent delirium induced by the excessive and prolonged
use of intoxicating liquors.
Traumatic delirium (Med.), a variety of delirium following
Syn: Insanity; frenzy; madness; derangement; aberration;
mania; lunacy; fury. See Insanity.