What does "lunacy" mean?

The state of being mad, insanity; A cyclical mental disease, apparently linked to the lunar phases.

What is a synonym for "lunacy"?

Common synonyms include: craziness, craziness, dementia, derangement, folly, insanity.

//ˈluː.nə.si// noun

noun ·Moderate ·High school level

Noun

1
The state of being mad, insanity; A cyclical mental disease, apparently linked to the lunar phases. countable, uncountable
2
foolish or senseless behavior wordnet
3
The state of being mad, insanity; Insanity implying legal irresponsibility. countable, uncountable
4
obsolete terms for legal insanity wordnet
5
Something deeply misguided. countable, uncountable
"Two days have passed since that day of lunacy. What a noise and a fuss and a chattering and an uproar there was! And what a welter of unseemliness and disorder and stupidity and bad manners! And I the cause of it all! Yet part of the scene was also ridiculous—at all events to myself it was so."