so ‧ bri ‧ e ‧ ty /səˈbraɪəti/ BrE AmE noun [uncountable] formal
[ Date: 1400-1500 ; Language: Old French ; Origin: sobrieté , from Latin sobrietas , from sobrius ; ⇨ ↑ sober 1 ]
1 . when someone is not drunk:
John had periods of sobriety, but always went back to drinking.
2 . behaviour that shows a serious attitude to life