alertness Definition

alert
adj alerter, alertest

1. Thinking and acting quickly.

Thesaurus: attentive, on the ball (slang), observant, wide-awake; Antonym: listless.
2. Watchful and aware of (a danger, etc).

Thesaurus: vigilant, ready, wary, watchful, on the qui vive, circumspect; Antonym: unwary.
Form: alert to something (especially)

noun

1. A warning of danger.

Thesaurus: signal, warning, alarm, admonition.
2. The period of time covered by such a warning.

verb

alerted, alerting
1. To warn them of (a danger); to make them aware of (a fact or circumstance).

Form: alert someone to something (usually)

Derivative: alertly
adverb

Derivative: alertness
noun

Idiom: on the alert

Watchful.

Etymology: 17c: from French alerte, from Italian all'erta to the watchtower.