Merriam-Webster Collegiate Dictionary - watchful

 adjective  Date: 15th century  1. archaic  a. not able or accustomed to sleep or rest ; wakeful  b. causing sleeplessness  c. spent in wakefulness ; sleepless  2. carefully observant or attentive ; being on the watch  • ~ly adverb  • ~ness noun Synonyms:  ~, vigilant, wide-awake, alert mean being on the lookout especially for danger or opportunity. ~ is the least explicit term the ~ eye of the department supervisor. vigilant suggests intense, unremitting, wary ~ness eternally vigilant in the safeguarding of democracy. wide-awake applies to ~ness for opportunities and developments more often than dangers wide-awake companies latched onto the new technology. alert stresses readiness or promptness in meeting danger or in seizing opportunity alert traders anticipated the stock market's slide.