Meaning of the word alertness in English

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

alertness

US /əˈlɝːt.nəs/
UK /əˈlɜːt.nəs/

Noun

the state of being watchful and quick to act; readiness

Example:
The guard maintained a high level of alertness throughout his shift.
Coffee can improve your mental alertness.