¹alert

watchful, vigilant, wide-awake, alert mean being on the lookout especially 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>.

intelligent, clever, alert, quick-witted mean mentally keen or quick. intelligent stresses success in coping with new situations and solving problems <an intelligent person could assemble it fast>. clever implies native ability or aptness and sometimes suggests a lack of more substantial qualities <clever with words>. alert stresses quickness in perceiving and understanding <alert to new technology>. quick-witted implies promptness in finding answers in debate or in devising expedients in moments of danger or challenge <no match for his quick-witted opponent>.