madness vs lunacy

madness and lunacy both are nouns.

Word	Noun	Adjective	Verb	Adverb
madness	Yes	No	No	No
lunacy	Yes	No	No	No

As nouns, madness and lunacy are synonyms defined as:

Other synonyms of madness include insaneness.

madness (noun)	lunacy (noun)
unrestrained excitement or enthusiasm	foolish or senseless behavior
the quality of being rash and foolish	obsolete terms for legal insanity
a feeling of intense anger
obsolete terms for legal insanity
an acute viral disease of the nervous system of warm-blooded animals (usually transmitted by the bite of a rabid animal); rabies is fatal if the virus reaches the brain