insanity
n.
1580s, "state of being insane," from Latin insanitatem (nominative insanitas) "unhealthfulness," noun of quality from insanus (see insane). Meaning "extreme folly" is from 1844.
〔李〕[in-;san;-ityn.] n.精神病； 极其愚蠢，愚行 ←san (L sanare,sanatum)=to heal 治愈