[watch.ful] adj (1548) 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 -- watch.ful.ly adv -- watch.ful.ness n syn watchful, vigilant, wide-awake, alert mean being on the lookout esp. for danger or opportunity. watchful is the least explicit term "the watchful eye of the department supervisor". vigilant suggests intense, unremitting, wary watchfulness "eternally vigilant in the safeguarding of democracy". wide-awake applies to watchfulness 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".