sanity
n. uncountablen. the state of having a healthy mind and being able to think or behave normally. It can also mean that a situation is sensible and calm.
n. the state of being mentally healthy and possessing sound judgment. Often used in a figurative sense to describe a return to rational or calm conditions in a chaotic environment.
I go for a walk every day to keep my sanity.
After a week of constant shouting and arguments, the family finally sat down to talk and restored some sanity to the house.
The judge's decision was hailed as a victory for sanity in a legal battle that had become increasingly irrational and driven by personal vendettas.
From Middle English sanite, sanyte, sanytee, from Middle French sanité, from Latin sānitās, from sānus (“healthy”) + -itās (“-ity”). By surface analysis, sane + -ity.
Commonly used in the phrase 'keep/lose one's sanity' or 'restore sanity to' a situation.