/ ˈsænəti; NAmE / noun [ U ]
1.
the state of having a normal healthy mind :
His behaviour was so strange that I began to doubt his sanity.
to keep / preserve your sanity
2.
the state of being sensible and reasonable :
After a series of road accidents the police pleaded for sanity among drivers.
OPP insanity
—see also sane
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WORD ORIGIN
late Middle English (in the sense health ): from Latin sanitas health, from sanus healthy. Current senses date from the early 17th cent.