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.

2. A morbid suspension of good sense or judgment, as through fanaticism. Dr. H. More.

Syn. -- Derangement; craziness; mania. See Insanity.

• (Of a person or group of people) the state of being mad, insanity.
  
• Something misguided.