Definition of "alertness" []

• The quality of being alert or on the alert; briskness; nimbleness; activity. (noun)

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• "The medium/high caffeine consumers who got the placebo reported a decrease in alertness and increased headache, neither of which were reported by those who received caffeine."
• "Unfortunately, the placebo takers also had unmistakable headaches and, temporarily, occasional decreases in alertness or energy."
• "The undead we encountered were a nice exercise in alertness, because some of them were invisible, and as we fought our way through them up to the parapet where the questgiver waited for us, I admired our solid teamwork."