<p><strong>Noun (plural, lunacies):</strong></p><ul><li>insanity; mental disorder</li><li>intermittent insanity, formerly believed to be related to phases of the moon</li><li>extreme foolishness or an instance of it (e.g., Her decision to resign was sheer lunacy)</li><li>unsoundness of mind sufficient to incapacitate one for civil transactions (a former legal term)</li></ul><p><strong>Synonyms:</strong></p><ul><li>craziness</li><li>aberration</li><li>mania</li><li>madness</li><li>dementia</li><li>derangement</li><li>stupidity</li><li>folly</li></ul><p><strong>Antonyms:</strong></p><ul><li>sanity</li><li>rationality</li></ul>