Reacting readily to stimuli or impressions, as hearing or eyesight; sensitive. Relating to an illness that has a rapid onset and follows a short but severe course. Having an acute angle. Acute, penetrating, shrewd imply a keenness of understanding, perception, or insight. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.