Insanity

Part of speech: noun

Pronunciation: /ɪnˈsænɪti/

Definitions

1. A state of severe mental illness that impairs rational thinking and judgment, or extreme foolishness in behavior or reasoning
2. A condition characterized by a profound disruption of mental functions causing irrational behavior and decision-making, or an extreme deviation from reason and normal thought processes
3. A mental state where one's perception of reality is distorted, leading to abnormal behavior or an inability to think clearly and logically

Etymology: Latin gave English a pair of near-twins here. "Insanus" meant "unsound, mad," built from "in-" (not) and "sanus" (sound, healthy), so the root idea is a mind or body that is not whole. Its partner "sanitas" meant "health," and the two words followed different paths into English: "sane" came from "sanus," while "insanity" pairs the prefix "in-" with "sanitas," the abstract noun for soundness. The result is a word that, in its Latin form, was built from a negative of a word meaning health. The English word therefore joins "in-" to "sanity" with a three-part build: the root "sane," the negating prefix "in-" meaning "lacking" or "without," and the suffix "-ity," which turns an adjective into a noun for a state or condition. Speakers could equally have arrived at it by starting from "insane" and adding "-ity," so the construction is traceable through either route.

Synonyms: madness, lunacy, derangement, psychosis, unreasonableness

Antonyms: sanity, rationality, normalcy, reason, sensitivity