sanityEnglishOxford American Thesaurussanity noun 1 she wondered if she was losing her sanity: soundness of mind, mental health, mental faculties, balance, balance of mind, stability, reason, rationality, saneness, lucidity, lucidness, sense, senses, wits, normality, right-mindedness. ▷antonyms insanity. 2 we are delighted that sanity has prevailed: sense, common sense, good sense, wisdom, prudence, judiciousness, practicality, reasonableness, rationality, soundness, sensibleness. ▷antonyms insanity.