Meaning of the word sanity in English

What does sanity mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

sanity

US /ˈsæn.ə.t̬i/
UK /ˈsæn.ə.ti/

Noun

the ability to think and behave in a normal and rational manner; sound mental health.

Example:
I began to doubt my own sanity
Antonym: