1580s, "state of being insane," from Latin insanitatem (nominative insanitas) "unhealthfulness," noun of quality from insanus (see insane). Meaning "extreme folly" is from 1844.
权威例句
1. Phillips murdered his wife, but got off on a plea of insanity.
菲利普斯谋杀了他的妻子,但以精神错乱为由逃脱了惩罚。
2. The insanity which ran in his family haunted him.
家族遗传的精神错乱困扰着他。
3. It was a period of collective insanity, of legalized murder and mayhem.
那是个集体丧失理智、谋杀与暴力合法化的时期。
4. The defence pleaded insanity, but the defendant was found guilty and sentenced.