Alert

Words referring to a mental state when the mind is working hard.

• What words refer to an alert mental state?
  be on your guard beware take heed be on the lookout watch
• What words describe someone who is alert?
  alert watchful vigilant keep your eyes peeled aware clear headed coherent wary mindful responsive sensitive
• What words describe someone who is not alert?
  unaware mindless unmindful bored disregard flighty heedless oblivious