"Delirium," meaning wild excitement or ecstasy, was originally a Latin word from the verb "deliare" ("deviate; be deranged") The literal meaning was "deviate from the furrow." A "delius" was thus a person who could not plough straight and was, therefore, crazy.
Other artists that have penned songs with the word "delirium" in the title include Ladyhawke
, Coheed and Cambria
, Motion City Soundtrack
and Ellie Goulding