lunacy C2+ Topic:Abstract Ideas US /ˈlunəsi/ UK /ˈluːnəsi/ See IPA manual Meanings 1 noun foolish or reckless behavior; insanity Crossing the river in that storm would be sheer lunacy. Thesaurus Synonyms 1 noun · foolish or reckless... madnessinsanityfollyfoolishnesscrazinessderangementabsurdity ↔ Opposites sanityreasonprudencesense Word family Related forms lunaticlunarlune Etymology AI details From lunatic + -cy, ultimately from Latin luna ('moon'), reflecting the old belief that madness was caused by the changing phases of the moon. luna Latin *lewk- Proto-Indo-European View etymology graph -> Topics Abstract Ideas Word Formation & Derivatives External links Google Images Cambridge Dictionary Wiktionary # lunacy **Type:** Word **Level:** C2+ **Part of speech:** noun **IPA (US):** /ˈlunəsi/ **IPA (UK):** /ˈluːnəsi/ ## Meanings 1. foolish or reckless behavior; insanity ## Examples - Crossing the river in that storm would be sheer lunacy. ## Synonyms - madness - insanity - folly - foolishness - craziness - derangement - absurdity ## Antonyms - sanity - reason - prudence - sense ## Related Forms - lunatic - lunar - lune ## Roots and Affixes - Root: luna - Root: *lewk- ## Etymology From lunatic + -cy, ultimately from Latin luna ('moon'), reflecting the old belief that madness was caused by the changing phases of the moon. ## AI Etymology Lunacy comes from lunatic + -cy, ultimately from Latin luna ('moon'), reflecting the old belief that madness was caused by the changing phases of the moon. The etymological trail includes Latin luna and Proto-Indo-European *lewk-. As a noun, lunacy means foolish or reckless behavior; insanity. The same family is visible in related forms such as lunatic, lunar, and lune. Morphologically, the word is built from the elements named in its history, so the modern form preserves a visible compound, prefix, or suffix structure. ## Topics - Abstract Ideas - Word Formation & Derivatives markdown