1 sharp, pointed, narrow:
The two roads meet at an acute angle.
2 severe, intense, critical, crucial, dangerous, grave, serious, severe:
This is the ward for patients with acute illnesses.
3 sharp, cutting, intense, severe, violent, penetrating, exquisite, excruciating, fierce, shooting, stabbing, piercing, sudden:
The onset of the disease is marked by acute pains in the abdomen.
4 keen, sharp, sensitive:
The bloodhound is known for its acute sense of smell.
5 keen, sharp-witted, shrewd, clever, ingenious, astute, sharp, canny, incisive, discerning, perceptive, perspicacious, intelligent, penetrating, insightful, percipient, wise, sensitive, discriminating; alert, aware, on the qui vive:
Such a circumstance could not be lost upon so acute an observer.