Lu"na*cy (?), n.; pl. Lunacies (#). [See Lunatic.]
1.
Insanity or madness; properly, the kind of insanity which is broken by intervals of reason, -- formerly supposed to be influenced by the changes of the moon; any form of unsoundness of mind, except idiocy; mental derangement or alienation.
Brande. Burrill.
Your kindred shuns your house
As beaten hence by your strange lunacy.
Shak.
2. A morbid suspension of good sense or judgment, as through fanaticism.
Dr. H. More.
Syn. -- Derangement; craziness; mania. See Insanity.
© Webster 1913.